diff --git a/201902654/10026.cpp b/201902654/10026.cpp
new file mode 100644
index 0000000..18cf87b
--- /dev/null
+++ b/201902654/10026.cpp
@@ -0,0 +1,74 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+char board[101][101];
+bool is_visit[101][101];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int N;
+    int normal_result = 0;
+    int abnormal_result = 0;
+    queue<pair<int, int> > Q;
+    cin >> N;
+    for (int i=0;i<N;i++) {
+      string line;
+      cin >> line;
+      for (int j=0;j<N;j++) {
+        board[i][j] = line.at(j);
+      }
+    }
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<N;x++) {
+        if (!is_visit[y][x]) {
+          normal_result++;
+          is_visit[y][x] = true;
+          Q.push(make_pair(x, y));
+          while (!Q.empty()) {
+            pair<int, int> top = Q.front(); Q.pop();
+            for (int i=0;i<4;i++) {
+              int nx = top.X + dx[i];
+              int ny = top.Y + dy[i];
+              if (0 <= nx && nx < N && 0 <= ny && ny < N && !is_visit[ny][nx] && board[ny][nx] == board[top.Y][top.X]) {
+                is_visit[ny][nx] = true;
+                Q.push(make_pair(nx, ny));
+              }
+            }
+          }
+        }
+      }
+    }
+    for (int i=0;i<N;i++) fill(is_visit[i], is_visit[i] + N, false);
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<N;x++) {
+        if (!is_visit[y][x]) {
+          abnormal_result++;
+          is_visit[y][x] = true;
+          Q.push(make_pair(x, y));
+          while (!Q.empty()) {
+            pair<int, int> top = Q.front(); Q.pop();
+            for (int i=0;i<4;i++) {
+              int nx = top.X + dx[i];
+              int ny = top.Y + dy[i];
+              if (0 <= nx && nx < N && 0 <= ny && ny < N && !is_visit[ny][nx] && (board[ny][nx] == board[top.Y][top.X] || (board[ny][nx] == 'R' && board[top.Y][top.X] == 'G') || (board[ny][nx] == 'G' && board[top.Y][top.X] == 'R'))) {
+                is_visit[ny][nx] = true;
+                Q.push(make_pair(nx, ny));
+              }
+            }
+          }
+        }
+      }
+    }
+    cout << normal_result << ' ' << abnormal_result;
+    return 0;
+}
diff --git a/201902654/1012.cpp b/201902654/1012.cpp
new file mode 100644
index 0000000..d84aa5d
--- /dev/null
+++ b/201902654/1012.cpp
@@ -0,0 +1,59 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int board[51][51];
+int is_visit[51][51];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int T;
+    cin >> T;
+    for (int i=0;i<T;i++) {
+      int M, N, K;
+      int result = 0;
+      queue<pair<int, int> > Q;
+      cin >> M >> N >> K;
+      for (int y=0;y<N;y++) {
+        fill(board[y], board[y] + M, 0);
+        fill(is_visit[y], is_visit[y] + M, false);
+      }
+      for (int i=0;i<K;i++) {
+        int x, y;
+        cin >> x >> y;
+        board[y][x] = 1;
+      }
+      for (int y=0;y<N;y++) {
+        for (int x=0;x<M;x++) {
+          if (board[y][x] == 1 && !is_visit[y][x]) {
+            result++;
+            Q.push(make_pair(x, y));
+            is_visit[y][x] = true;
+            while (!Q.empty()) {
+              pair<int, int> top = Q.front(); Q.pop();
+              for (int i=0;i<4;i++) {
+                int nx = top.X + dx[i];
+                int ny = top.Y + dy[i];
+                if (0 <= nx && nx < M && 0 <= ny && ny < N && is_visit[ny][nx] == false && board[ny][nx] == 1) {
+                  is_visit[ny][nx] = true;
+                  Q.push(make_pair(nx, ny));
+                }
+              }
+            }
+          }
+        }
+      }
+      cout << result << '\n';
+    }
+
+    return 0;
+}
diff --git a/201902654/1021.cpp b/201902654/1021.cpp
new file mode 100644
index 0000000..d7511ac
--- /dev/null
+++ b/201902654/1021.cpp
@@ -0,0 +1,61 @@
+#include <string>
+#include <deque>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int N, M;
+    int result = 0;
+    deque<int> D;
+    cin >> N >> M;
+    for (int i=0;i<N;i++) {
+      D.push_back(i+1);
+    }
+    for (int i=0;i<M;i++) {
+      int value;
+      cin >> value;
+      int front_count = 0;
+      int back_count = 0;
+      while (D.front() != value) {
+        D.push_back(D.front());
+        D.pop_front();
+        front_count++;
+      }
+      for (int i=0;i<front_count;i++) {
+        D.push_front(D.back());
+        D.pop_back();
+      }
+      while (D.front() != value) {
+        D.push_front(D.back());
+        D.pop_back();
+        back_count++;
+      }
+      for (int i=0;i<back_count;i++) {
+        D.push_back(D.front());
+        D.pop_front();
+      }
+
+      if (front_count > back_count) {
+        for (int i=0;i<back_count;i++) {
+          D.push_front(D.back());
+          D.pop_back();
+        }
+        D.pop_front();
+        result = result + back_count;
+      } else {
+        for (int i=0;i<front_count;i++) {
+          D.push_back(D.front());
+          D.pop_front();
+        }
+        D.pop_front();
+        result = result + front_count;
+      }
+    }
+    cout << result;
+
+    return 0;
+}
diff --git a/201902654/1074.cpp b/201902654/1074.cpp
new file mode 100644
index 0000000..431aa3c
--- /dev/null
+++ b/201902654/1074.cpp
@@ -0,0 +1,29 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+#define X first
+#define Y second
+int order;
+int N, r, c;
+
+int record(int N, int x, int y) {
+  int half = pow(2, N-1);
+  if (N == 0) {
+    return 0;
+  }
+  if (x < half && y < half) return record(N-1, x, y);
+  if (x >= half && y < half) return half * half * 1 + record(N-1, x-half, y);
+  if (x < half && y >= half) return half * half * 2 + record(N-1, x, y-half);
+  if (x >= half && y >= half) return half * half * 3 + record(N-1, x-half, y-half);
+}
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> N >> r >> c;
+
+    cout << record(N, c, r);
+
+
+    return 0;
+}
diff --git a/201902654/10773.cpp b/201902654/10773.cpp
new file mode 100644
index 0000000..7d1a2d0
--- /dev/null
+++ b/201902654/10773.cpp
@@ -0,0 +1,35 @@
+#include <string>
+#include <stack>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int K;
+    long result = 0;
+    stack<int> stack;
+    cin >> K;
+
+    for (int i=0;i<K;i++) {
+      int input;
+      cin >> input;
+
+      if (input == 0) {
+        stack.pop();
+      } else {
+        stack.push(input);
+      }
+    }
+
+    while (!stack.empty()) {
+      result = result + stack.top();
+      stack.pop();
+    }
+
+    cout << result;
+
+    return 0;
+}
diff --git a/201902654/10799.cpp b/201902654/10799.cpp
new file mode 100644
index 0000000..f5c504c
--- /dev/null
+++ b/201902654/10799.cpp
@@ -0,0 +1,32 @@
+#include <string>
+#include <stack>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    string line;
+    stack<char> S;
+    long result = 0;
+    cin >> line;
+    for (int i=0;i<line.size();i++) {
+      char ch = line.at(i);
+      if (ch == '(') {
+        S.push(ch);
+      } else {
+        if (line.at(i - 1) == '(') {
+          S.pop();
+          result += S.size();
+        } else {
+          S.pop();
+          result++;
+        }
+      }
+    }
+    cout << result;
+
+    return 0;
+}
diff --git a/201902654/10807.cpp b/201902654/10807.cpp
new file mode 100644
index 0000000..d5c4936
--- /dev/null
+++ b/201902654/10807.cpp
@@ -0,0 +1,24 @@
+#include <string>
+#include <vector>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int N;
+    cin >> N;
+    int count[201];
+    fill(count, count+201, 0);
+    for (int i=0;i<N;i++) {
+      int val;
+      cin >> val;
+      count[val + 100]++;
+    }
+    int find;
+    cin >> find;
+    cout << count[find+100];
+
+    return 0;
+}
diff --git a/201902654/10808.cpp b/201902654/10808.cpp
new file mode 100644
index 0000000..40e4dc1
--- /dev/null
+++ b/201902654/10808.cpp
@@ -0,0 +1,20 @@
+#include <iostream>
+#include <vector>
+#include <string>
+
+using namespace std;
+
+int main(void) {
+  string s;
+  getline(cin, s);
+  vector<int> alpha(26, 0);
+
+  for (int i=0;i<s.length();++i){
+    int index = s[i] - 'a';
+    ++alpha[index];
+  }
+
+  for (int iter : alpha) {
+    cout << iter << ' ';
+  }
+}
diff --git a/201902654/10828.cpp b/201902654/10828.cpp
new file mode 100644
index 0000000..7833393
--- /dev/null
+++ b/201902654/10828.cpp
@@ -0,0 +1,46 @@
+#include <stack>
+#include <string>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int N;
+    stack<int> stack;
+    cin >> N;
+    for (int i=0;i<N;i++) {
+      string command;
+      cin >> command;
+      if (command == "push") {
+        int val;
+        cin >> val;
+        stack.push(val);
+      } else if (command == "pop") {
+        if (stack.empty()) {
+          cout << -1 << '\n';
+        } else {
+          cout << stack.top() << '\n';
+          stack.pop();
+        }
+      } else if (command == "size") {
+        cout << stack.size() << '\n';
+      } else if (command == "empty") {
+        if (stack.empty()) {
+          cout << 1 << '\n';
+        } else {
+          cout << 0 << '\n';
+        }
+      } else {
+        if (stack.empty()) {
+          cout << -1 << '\n';
+        } else {
+          cout << stack.top() << '\n';
+        }
+      }
+    }
+
+    return 0;
+}
diff --git a/201902654/10845.cpp b/201902654/10845.cpp
new file mode 100644
index 0000000..8069f29
--- /dev/null
+++ b/201902654/10845.cpp
@@ -0,0 +1,42 @@
+#include <string>
+#include <queue>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    queue<int> Q;
+    int N;
+    cin >> N;
+    for (int i=0;i<N;i++) {
+      string command;
+      cin >> command;
+      if (command == "push") {
+        int value;
+        cin >> value;
+
+        Q.push(value);
+      } else {
+        if (command == "pop") {
+          cout << ((Q.size() == 0) ? -1 : Q.front());
+          if (Q.size() != 0) {
+            Q.pop();
+          }
+        } else if (command == "size") {
+          cout << Q.size();
+        } else if (command == "empty") {
+          cout << ((Q.size() == 0) ? 1 : 0);
+        } else if (command == "front") {
+          cout << ((Q.size() == 0) ? -1 : Q.front());
+        } else if (command == "back") {
+          cout << ((Q.size() == 0) ? -1 : Q.back());
+        }
+        cout << '\n';
+      }
+    }
+
+    return 0;
+}
diff --git a/201902654/10866.cpp b/201902654/10866.cpp
new file mode 100644
index 0000000..f1daf88
--- /dev/null
+++ b/201902654/10866.cpp
@@ -0,0 +1,47 @@
+#include <string>
+#include <deque>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    deque<int> D;
+    int N;
+    cin >> N;
+    for (int i=0;i<N;i++) {
+      string command;
+      cin >> command;
+      if (command == "push_front") {
+        int value;
+        cin >> value;
+        D.push_front(value);
+      } else if (command == "push_back") {
+        int value;
+        cin >> value;
+        D.push_back(value);
+      } else if (command == "pop_front") {
+        cout << ((D.size() == 0) ? -1 : D.front()) << '\n';
+        if (D.size() != 0) {
+          D.pop_front();
+        }
+      } else if (command == "pop_back") {
+        cout << ((D.size() == 0) ? -1 : D.back()) << '\n';
+        if (D.size() != 0) {
+          D.pop_back();
+        }
+      } else if (command == "size") {
+        cout << D.size() << '\n';
+      } else if (command == "empty") {
+        cout << ((D.size() == 0) ? 1 : 0) << '\n';
+      } else if (command == "front") {
+        cout << ((D.size() == 0) ? -1 : D.front()) << '\n';
+      } else if (command == "back") {
+        cout << ((D.size() == 0) ? -1 : D.back()) << '\n';
+      }
+    }
+
+    return 0;
+}
diff --git a/201902654/10871.cpp b/201902654/10871.cpp
new file mode 100644
index 0000000..86fa64f
--- /dev/null
+++ b/201902654/10871.cpp
@@ -0,0 +1,18 @@
+#include <vector>
+#include <iostream>
+
+using namespace std;
+
+int main(void) {
+  ios::sync_with_stdio(0);
+  cin.tie(0);
+  int N, X;
+  cin >> N >> X;
+  for(int i=0;i<N;++i) {
+    int num;
+    cin >> num;
+    if (num < X) {
+      cout << num << ' ';
+    }
+  }
+}
diff --git a/201902654/11003.cpp b/201902654/11003.cpp
new file mode 100644
index 0000000..5578db4
--- /dev/null
+++ b/201902654/11003.cpp
@@ -0,0 +1,39 @@
+#include <string>
+#include <deque>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    deque<pair<int, int> > D;
+    int N, L;
+    cin >> N >> L;
+    int arr[N];
+    for (int i=0;i<N;i++) {
+        cin >> arr[i];
+    }
+    D.push_back(make_pair(arr[0], L));
+    for (int i=0;i<N;i++) {
+        if (i != 0) {
+            int pop_sum = 0;
+            while (!D.empty() && D.back().first >= arr[i]) {
+                pop_sum += D.back().second;
+                D.pop_back();
+            }
+            D.push_back(make_pair(arr[i], pop_sum + 1));
+        }
+        pair<int, int> front = D.front();
+        if (front.second == 1) {
+            D.pop_front();
+        } else {
+            D.pop_front();
+            D.push_front(make_pair(front.first, front.second - 1));
+        }
+        cout << front.first << ' ';
+    }
+
+    return 0;
+}
diff --git a/201902654/1158.cpp b/201902654/1158.cpp
new file mode 100644
index 0000000..e269c67
--- /dev/null
+++ b/201902654/1158.cpp
@@ -0,0 +1,41 @@
+#include <string>
+#include <list>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int N, K;
+    cin >> N >> K;
+    list<int> L,result;
+    auto cursor = L.begin();
+    for (int i=0;i<N;++i) {
+      L.push_back(i+1);
+    }
+    for (int i=0;i<N;i++) {
+      for (int j=0;j<K-1;j++) {
+        if (cursor == L.end()) {
+          cursor = L.begin();
+        }
+        cursor++;
+      }
+      if (cursor == L.end()) {
+        cursor = L.begin();
+      }
+      result.push_back(*cursor);
+      cursor = L.erase(cursor);
+    }
+    cout << '<';
+    for (list<int>::iterator it = result.begin();it != result.end();it++) {
+      cout << *it;
+      if (it != --result.end()) {
+        cout << ", ";
+      }
+    }
+    cout << '>';
+
+    return 0;
+}
diff --git a/201902654/11729.cpp b/201902654/11729.cpp
new file mode 100644
index 0000000..d98d7e5
--- /dev/null
+++ b/201902654/11729.cpp
@@ -0,0 +1,56 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+vector<stack<int> > stacks;
+int result = 0;
+
+void move(int n, int from, int to, int middle, bool is_print) {
+  if (n == stacks[from].top()) {
+    result++;
+    stacks[to].push(stacks[from].top());
+    stacks[from].pop();
+    if (is_print) {
+      cout << from + 1 << ' ' << to + 1 << '\n';
+    }
+  } else {
+    move(n-1, from, middle, to, is_print);
+    result++;
+    stacks[to].push(stacks[from].top());
+    stacks[from].pop();
+    if (is_print) {
+      cout << from + 1 << ' ' << to + 1 << '\n';
+    }
+    move(n-1, middle, to, from, is_print);
+  }
+}
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    stacks.push_back(stack<int>());
+    stacks.push_back(stack<int>());
+    stacks.push_back(stack<int>());
+    int N;
+    cin >> N;
+    for (int i=N;i>0;i--) {
+      stacks[0].push(i);
+    }
+    move(N, 0, 2, 1, false);
+    for (int i=N;i>0;i--) {
+      stacks[0].push(i);
+    }
+    stacks[2] = stack<int>();
+    cout << result << '\n';
+    move(N, 0, 2, 1, true);
+
+    return 0;
+}
diff --git a/201902654/13549.cpp b/201902654/13549.cpp
new file mode 100644
index 0000000..97fe0fa
--- /dev/null
+++ b/201902654/13549.cpp
@@ -0,0 +1,41 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+#include <limits>
+
+using namespace std;
+#define X first
+#define Y second
+int N, K;
+int min_time[200001];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    fill(min_time, min_time + 200001, __INT_MAX__);
+    cin >> N >> K;
+    queue<pair<int, int> > Q;
+    min_time[N] = 0;
+    Q.push(make_pair(N, 0));
+    while (!Q.empty()) {
+      pair<int, int> top = Q.front(); Q.pop();
+      if (top.X - 1 >= 0 && min_time[top.X - 1] > top.Y + 1) {
+        min_time[top.X - 1] = top.Y + 1;
+        Q.push(make_pair(top.X - 1, top.Y + 1));
+      }
+      if (top.X + 1 < 200001 && min_time[top.X + 1] > top.Y + 1) {
+        min_time[top.X + 1] = top.Y + 1;
+        Q.push(make_pair(top.X + 1, top.Y + 1));
+      }
+      if (top.X * 2 < 200001 && min_time[top.X * 2] > top.Y) {
+        min_time[top.X * 2] = top.Y;
+        Q.push(make_pair(top.X * 2, top.Y));
+      }
+    }
+    cout << min_time[K];
+
+    return 0;
+}
diff --git a/201902654/1406.cpp b/201902654/1406.cpp
new file mode 100644
index 0000000..2ba73df
--- /dev/null
+++ b/201902654/1406.cpp
@@ -0,0 +1,45 @@
+#include <string>
+#include <list>
+#include <iostream>
+
+using namespace std;
+
+int main(void) {
+  ios::sync_with_stdio(0);
+  cin.tie(0);
+
+  string N;
+  int M;
+  cin >> N;
+  list<char> L;
+  for (char ch : N) {
+    L.push_back(ch);
+  }
+  auto cursor = L.end();
+  cin >> M;
+  for (int i=0;i<M;++i) {
+    char op;
+    cin >> op;
+    if (op == 'L') {
+      if (cursor != L.begin()) {
+        cursor--;
+      }
+    } else if (op == 'D') {
+      if (cursor != L.end()) {
+        cursor++;
+      }
+    } else if (op == 'B') {
+      if (cursor != L.begin()) {
+        cursor--;
+        cursor = L.erase(cursor);
+      }
+    } else if (op == 'P') {
+      char ch;
+      cin >> ch;
+      L.insert(cursor, ch);
+    }
+  }
+  for (char ch : L) {
+    cout << ch;
+  }
+}
diff --git a/201902654/14442.cpp b/201902654/14442.cpp
new file mode 100644
index 0000000..1bb9a88
--- /dev/null
+++ b/201902654/14442.cpp
@@ -0,0 +1,65 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+#include <limits>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int map[1001][1001];
+int dist[11][1001][1001];
+int N, M, K;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    for (int i=0;i<11;i++) {
+      for (int j=0;j<1001;j++) {
+        fill(dist[i][j], dist[i][j] + 1001, -1);
+      }
+    }
+    cin >> N >> M >> K;
+    for (int i=0;i<N;i++) {
+      string line;
+      cin >> line;
+      for (int j=0;j<M;j++) {
+        map[i][j] = line.at(j) - '0';
+      }
+    }
+    queue<tuple<int, int, int> > Q;
+    dist[0][0][0] = 1;
+    Q.push(make_tuple(0, 0, 0));
+    while (!Q.empty()) {
+      tuple<int, int, int> top = Q.front(); Q.pop();
+      int x = get<0>(top);
+      int y = get<1>(top);
+      int broken_wall_count = get<2>(top);
+      for (int i=0;i<4;i++) {
+        int nx = x + dx[i];
+        int ny = y + dy[i];
+        if (0 <= nx && nx < M && 0 <= ny && ny < N) {
+          bool is_wall = map[ny][nx] == 1;
+          int next_wall_count = is_wall ? broken_wall_count + 1 : broken_wall_count;
+          if (next_wall_count <= K && dist[next_wall_count][ny][nx] == -1) {
+            dist[next_wall_count][ny][nx] = dist[broken_wall_count][y][x] + 1;
+            Q.push(make_tuple(nx, ny, next_wall_count));
+          }
+        }
+      }
+    }
+    int result = __INT_MAX__;
+    for (int i=0;i<=K;i++) {
+      if (dist[i][N-1][M-1] != -1) {
+        result = min(result, dist[i][N-1][M-1]);
+      }
+      // cout << dist[i][N-1][M-1];
+    }
+    cout << ((result == __INT_MAX__) ? -1 : result);
+
+    return 0;
+}
diff --git a/201902654/1475.cpp b/201902654/1475.cpp
new file mode 100644
index 0000000..442142c
--- /dev/null
+++ b/201902654/1475.cpp
@@ -0,0 +1,26 @@
+#include <string>
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+int main(void) {
+  ios::sync_with_stdio(0);
+  cin.tie(0);
+
+  string N;
+  vector<int> arr(10, 0);
+  getline(cin, N);
+  for (char ch : N) {
+    ++arr[ch - '0'];
+  }
+  arr[6] = (arr[6] + arr[9] + 1) / 2;
+  arr[9] = 0;
+  int max = 0;
+  for (int iter : arr) {
+    if (max < iter) {
+      max = iter;
+    }
+  }
+  cout << max;
+}
diff --git a/201902654/1629.cpp b/201902654/1629.cpp
new file mode 100644
index 0000000..a8ccf7c
--- /dev/null
+++ b/201902654/1629.cpp
@@ -0,0 +1,33 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+
+long long POW(int a, int b, int c) {
+  if (b == 1) return a % c;
+  long long val = POW(a, b/2, c);
+  val = val * val % c;
+  if (b % 2 == 0) {
+    return val;
+  } else {
+    return val * a % c;
+  }
+}
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int A, B, C;
+    cin >> A >> B >> C;
+
+    cout << POW(A, B, C);
+    return 0;
+}
diff --git a/201902654/1644.cpp b/201902654/1644.cpp
new file mode 100644
index 0000000..784f1cd
--- /dev/null
+++ b/201902654/1644.cpp
@@ -0,0 +1,44 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+int count_divider[4000001];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    vector<int> prime_numbers;
+    for (int i=2;i<=4000000;i++) {
+      for (int index=i;index<=4000000;index+=i) {
+        ++count_divider[index];
+      }
+    }
+    for (int i=2;i<=4000000;i++) {
+      if (count_divider[i] == 1) {
+        prime_numbers.push_back(i);
+      }
+    }
+    int result = 0;
+    long long N;
+    cin >> N;
+    vector<long long> sub_sum;
+    sub_sum.push_back(0);
+    for (int i=1;i<=prime_numbers.size();i++) {
+      sub_sum.push_back(sub_sum[i-1] + prime_numbers[i-1]);
+    }
+    int end = 0;
+    int length = sub_sum.size();
+    for (int start=0;start<length;start++) {
+      while (end < length) {
+        if (sub_sum[end] - sub_sum[start] >= N) {
+          if (sub_sum[end] - sub_sum[start] == N) {
+            result++;
+          }
+          break;
+        }
+        end++;
+      }
+    }
+    cout << result;
+
+    return 0;
+}
diff --git a/201902654/1697.cpp b/201902654/1697.cpp
new file mode 100644
index 0000000..67c54e8
--- /dev/null
+++ b/201902654/1697.cpp
@@ -0,0 +1,46 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int min_time[100001];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    fill(min_time, min_time+100001, -1);
+
+    int N, K;
+    queue<int> Q;
+    cin >> N >> K;
+    min_time[N] = 0;
+    Q.push(N);
+    while (!Q.empty()) {
+      int top = Q.front(); Q.pop();
+      if (top == K) {
+        break;
+      }
+      if (top - 1 >= 0 && min_time[top - 1] == -1) {
+        min_time[top - 1] = min_time[top] + 1;
+        Q.push(top - 1);
+      }
+      if (top + 1 < 100001 && min_time[top + 1] == -1) {
+        min_time[top + 1] = min_time[top] + 1;
+        Q.push(top + 1);
+      }
+      if (top * 2 < 100001 && min_time[top * 2] == -1) {
+        min_time[top * 2] = min_time[top] + 1;
+        Q.push(top * 2);
+      }
+    }
+    cout << min_time[K];
+
+    return 0;
+}
diff --git a/201902654/17298.cpp b/201902654/17298.cpp
new file mode 100644
index 0000000..721d07b
--- /dev/null
+++ b/201902654/17298.cpp
@@ -0,0 +1,30 @@
+#include <string>
+#include <stack>
+#include <iostream>
+#include <algorithm>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int N;
+    cin >> N;
+    stack<pair<int, int> > stack;
+    int result[N];
+    fill(result, result+N, -1);
+    for (int i=0;i<N;i++) {
+        int input;
+        cin >> input;
+        while (!stack.empty() && stack.top().second < input) {
+            result[stack.top().first] = input;
+            stack.pop();
+        }
+        stack.push(make_pair(i, input));
+    }
+    for (int iter : result) {
+        cout << iter << ' ';
+    }
+
+    return 0;
+}
diff --git a/201902654/17478.cpp b/201902654/17478.cpp
new file mode 100644
index 0000000..bfd2a98
--- /dev/null
+++ b/201902654/17478.cpp
@@ -0,0 +1,38 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+int N;
+
+void print_dash(int count) {
+  for (int i=0;i<count;i++) {
+    cout << "____";
+  }
+}
+
+void print(int count, int N) {
+  print_dash(count);
+  cout << "\"재귀함수가 뭔가요?\"" << '\n';
+  if (count == N) {
+    print_dash(count);
+    cout << "\"재귀함수는 자기 자신을 호출하는 함수라네\""<< '\n';
+  } else {
+    print_dash(count);
+    cout << "\"잘 들어보게. 옛날옛날 한 산 꼭대기에 이세상 모든 지식을 통달한 선인이 있었어."<< '\n';
+    print_dash(count);
+    cout << "마을 사람들은 모두 그 선인에게 수많은 질문을 했고, 모두 지혜롭게 대답해 주었지."<< '\n';
+    print_dash(count);
+    cout << "그의 답은 대부분 옳았다고 하네. 그런데 어느 날, 그 선인에게 한 선비가 찾아와서 물었어.\""<< '\n';
+    print(count+1, N);
+  }
+  print_dash(count);
+  cout << "라고 답변하였지." << '\n';
+}
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> N;
+    cout << "어느 한 컴퓨터공학과 학생이 유명한 교수님을 찾아가 물었다." << '\n';
+    print(0, N);
+    return 0;
+}
diff --git a/201902654/1780.cpp b/201902654/1780.cpp
new file mode 100644
index 0000000..6827f9b
--- /dev/null
+++ b/201902654/1780.cpp
@@ -0,0 +1,51 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int counts[3];
+int board[2200][2200];
+int N;
+
+void recursion(int N, int init_x, int init_y) {
+  int comp = board[init_y][init_x];
+  bool is_same = true;
+  for (int y = init_y; y < N + init_y; y++) {
+    for (int x = init_x; x < N + init_x; x++) {
+      if (board[y][x] != comp) is_same = false;
+    }
+  }
+  if (is_same) {
+    counts[comp + 1]++;
+  } else {
+    int w = N/3;
+    recursion(N/3, init_x, init_y);
+    recursion(N/3, init_x+w*1, init_y);
+    recursion(N/3, init_x+w*2, init_y);
+    recursion(N/3, init_x, init_y+w*1);
+    recursion(N/3, init_x+w*1, init_y+w*1);
+    recursion(N/3, init_x+w*2, init_y+w*1);
+    recursion(N/3, init_x, init_y+w*2);
+    recursion(N/3, init_x+w*1, init_y+w*2);
+    recursion(N/3, init_x+w*2, init_y+w*2);
+  }
+}
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> N;
+    for (int i=0;i<N;i++) {
+      for (int j=0;j<N;j++) {
+        cin >> board[i][j];
+      }
+    }
+    recursion(N, 0, 0);
+    cout << counts[0] << '\n';
+    cout << counts[1] << '\n';
+    cout << counts[2] << '\n';
+
+    return 0;
+}
diff --git a/201902654/1806.cpp b/201902654/1806.cpp
new file mode 100644
index 0000000..ae24c9a
--- /dev/null
+++ b/201902654/1806.cpp
@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int N, S;
+    cin >> N >> S;
+    int arr[N];
+    for (int i=0;i<N;i++) {
+      cin >> arr[i];
+    }
+    int sub_sum[N+1];
+    sub_sum[0] = 0;
+    for (int i=1;i<=N;i++) {
+      sub_sum[i] = sub_sum[i-1] + arr[i-1];
+    }
+    int end = N;
+    int result = __INT_MAX__;
+    for (int start=N;start>=0;start--) {
+      while (end >= 0) {
+        if (sub_sum[start] - sub_sum[end] >= S) {
+          result = min(result, start - end);
+          break;
+        }
+        end--;
+      }
+    }
+    cout << ((result == __INT_MAX__) ? 0 : result);
+
+    return 0;
+}
diff --git a/201902654/18258.cpp b/201902654/18258.cpp
new file mode 100644
index 0000000..8069f29
--- /dev/null
+++ b/201902654/18258.cpp
@@ -0,0 +1,42 @@
+#include <string>
+#include <queue>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    queue<int> Q;
+    int N;
+    cin >> N;
+    for (int i=0;i<N;i++) {
+      string command;
+      cin >> command;
+      if (command == "push") {
+        int value;
+        cin >> value;
+
+        Q.push(value);
+      } else {
+        if (command == "pop") {
+          cout << ((Q.size() == 0) ? -1 : Q.front());
+          if (Q.size() != 0) {
+            Q.pop();
+          }
+        } else if (command == "size") {
+          cout << Q.size();
+        } else if (command == "empty") {
+          cout << ((Q.size() == 0) ? 1 : 0);
+        } else if (command == "front") {
+          cout << ((Q.size() == 0) ? -1 : Q.front());
+        } else if (command == "back") {
+          cout << ((Q.size() == 0) ? -1 : Q.back());
+        }
+        cout << '\n';
+      }
+    }
+
+    return 0;
+}
diff --git a/201902654/1874.cpp b/201902654/1874.cpp
new file mode 100644
index 0000000..65dca48
--- /dev/null
+++ b/201902654/1874.cpp
@@ -0,0 +1,45 @@
+#include <string>
+#include <stack>
+#include <iostream>
+#include <list>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int max = 0;
+    stack<int> stack;
+    int n;
+    cin >> n;
+    int arr[n];
+    list<char> result;
+    for (int i=0;i<n;i++) {
+      int input;
+      cin >> input;
+      arr[i] = input;
+    }
+    for (int i=0;i<n;i++) {
+      int value = arr[i];
+      if (value > max) {
+        for (int j=0;j<value - max;j++) {
+          stack.push(j + max + 1);
+          result.push_back('+');
+        }
+        max = value;
+        stack.pop();
+        result.push_back('-');
+      } else if (!stack.empty() && stack.top() == value) {
+        stack.pop();
+        result.push_back('-');
+      } else {
+        cout << "NO";
+        return 0;
+      }
+    }
+    for (char iter : result) {
+      cout << iter << '\n';
+    }
+
+    return 0;
+}
diff --git a/201902654/1926.cpp b/201902654/1926.cpp
new file mode 100644
index 0000000..7ebfdae
--- /dev/null
+++ b/201902654/1926.cpp
@@ -0,0 +1,58 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+
+int board[501][501];
+bool is_visit[501][501];
+int dx[4] = {1, -1, 0, 0};
+int dy[4] = {0, 0, 1, -1};
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int n, m;
+    cin >> n >> m;
+    int count_result = 0;
+    int area_result = 0;
+    queue<pair<int, int> > Q;
+    for (int i=0;i<n;i++) {
+      for (int j=0;j<m;j++) {
+        cin >> board[i][j];
+      }
+    }
+
+    for (int i=0;i<n;i++) {
+      for (int j=0;j<m;j++) {
+        if (board[i][j] == 1 && !is_visit[i][j]) {
+          count_result++;
+          int area = 0;
+          Q.push(make_pair(j, i));
+          is_visit[i][j] = true;
+          while (!Q.empty()) {
+            area++;
+            pair<int, int> top = Q.front(); Q.pop();
+            for (int k=0;k<4;k++) {
+              int nx = top.X + dx[k];
+              int ny = top.Y + dy[k];
+              if (0 <= nx && nx < m && 0 <= ny && ny < n && board[ny][nx] == 1 && !is_visit[ny][nx]) {
+                is_visit[ny][nx] = true;
+                Q.push(make_pair(nx, ny));
+              }
+            }
+          }
+          area_result = max(area_result, area);
+        }
+      }
+    }
+    cout << count_result << '\n' << area_result;
+
+    return 0;
+}
diff --git a/201902654/2146.cpp b/201902654/2146.cpp
new file mode 100644
index 0000000..b1300d3
--- /dev/null
+++ b/201902654/2146.cpp
@@ -0,0 +1,94 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int N;
+int board[101][101];
+int min_length[101][101];
+bool is_visit[101][101];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> N;
+    for (int y=0;y<N;y++) {
+      fill(min_length[y], min_length[y] + 101, __INT_MAX__);
+    }
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<N;x++) {
+        cin >> board[y][x];
+      }
+    }
+    int area = 1;
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<N;x++) {
+        if (!is_visit[y][x] && board[y][x] > 0) {
+          queue<pair<int, int> > Q;
+          Q.push(make_pair(x, y));
+          is_visit[y][x] = true;
+          board[y][x] = area;
+          while (!Q.empty()) {
+            pair<int, int> top = Q.front(); Q.pop();
+            for (int i=0;i<4;i++) {
+              int nx = top.X + dx[i];
+              int ny = top.Y + dy[i];
+              if (0 <= nx && nx < N && 0 <= ny && ny < N && !is_visit[ny][nx] && board[ny][nx] > 0) {
+                is_visit[ny][nx] = true;
+                board[ny][nx] = area;
+                Q.push(make_pair(nx, ny));
+              }
+            }
+          }
+
+          area++;
+        }
+      }
+    }
+    // cout << "#############" << '\n';
+    // for (int y=0;y<N;y++) {
+    //   for (int x=0;x<N;x++) {
+    //     cout << board[y][x] << ' ';
+    //   }
+    //   cout << '\n';
+    // }
+    int result = __INT_MAX__;
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<N;x++) {
+        if (board[y][x] != 0 && ((x != 0 && board[y][x-1] == 0) || (x != N-1 && board[y][x+1] == 0) || (y != 0 && board[y-1][x] == 0) || (y != N-1 && board[y+1][x] == 0))) {
+          // cout << x << ' ' << y << '\n';
+          queue<tuple<int, int, int, int> > Q;
+          Q.push(make_tuple(x, y, board[y][x], 0));
+          min_length[y][x] = 0;
+          while (!Q.empty()) {
+            tuple<int, int, int, int> top = Q.front(); Q.pop();
+            int x = get<0>(top);
+            int y = get<1>(top);
+            int area = get<2>(top);
+            int length = get<3>(top);
+            for (int i=0;i<4;i++) {
+              int nx = x + dx[i];
+              int ny = y + dy[i];
+              if (0 <= nx && nx < N && 0 <= ny && ny < N && length + 1 <= result) {
+                // cout << "^^" << '\n';
+                if (board[ny][nx] == 0 && min_length[ny][nx] > length + 1) {
+                  min_length[ny][nx] = length + 1;
+                  Q.push(make_tuple(nx, ny, area, length + 1));
+                } else if (board[ny][nx] != 0 && board[ny][nx] != area) {
+                  result = min(result, length);
+                  // cout << length << '\n';
+                  queue<tuple<int, int, int, int> > empty;
+                  Q.swap(empty);
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+    cout << result;
+
+    return 0;
+}
diff --git a/201902654/2164.cpp b/201902654/2164.cpp
new file mode 100644
index 0000000..6ce1403
--- /dev/null
+++ b/201902654/2164.cpp
@@ -0,0 +1,25 @@
+#include <string>
+#include <queue>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    queue<int> Q;
+    int N;
+    cin >> N;
+    for (int i=0;i<N;i++) {
+      Q.push(i+1);
+    }
+    for (int i=0;i<N-1;i++) {
+      Q.pop();
+      Q.push(Q.front());
+      Q.pop();
+    }
+    cout << Q.front();
+
+    return 0;
+}
diff --git a/201902654/2178.cpp b/201902654/2178.cpp
new file mode 100644
index 0000000..aab3c42
--- /dev/null
+++ b/201902654/2178.cpp
@@ -0,0 +1,51 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+#include <string>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int board[101][101];
+int is_visit[101][101];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int N, M;
+    int result = 1000000000;
+    queue<tuple<int, int, int> > Q; // X Y val
+    cin >> N >> M;
+    for (int i=0;i<N;i++) {
+      string line;
+      cin >> line;
+      for (int j=0;j<M;j++) {
+        board[i][j] = line.at(j) - '0';
+      }
+    }
+    Q.push(make_tuple(0, 0, 1));
+    is_visit[0][0] = true;
+    while (!Q.empty()) {
+      tuple<int, int, int> top = Q.front(); Q.pop();
+      if (get<0>(top) == M - 1 && get<1>(top) == N - 1) {
+        result = min(result, get<2>(top));
+      }
+      for (int i=0;i<4;i++) {
+        int nx = get<0>(top) + dx[i];
+        int ny = get<1>(top) + dy[i];
+        if (0 <= nx && nx < M && 0 <= ny && ny < N && !is_visit[ny][nx] && board[ny][nx] == 1) {
+          is_visit[ny][nx] = true;
+          Q.push(make_tuple(nx, ny, get<2>(top) + 1));
+        }
+      }
+    }
+    cout << result;
+
+    return 0;
+}
diff --git a/201902654/2206.cpp b/201902654/2206.cpp
new file mode 100644
index 0000000..52447b9
--- /dev/null
+++ b/201902654/2206.cpp
@@ -0,0 +1,65 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int map[1001][1001];
+int MAX_BREAKABLE_WALL = 1;
+int dist[2][1001][1001];
+int N, M;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    for (int i=0;i<2;i++) {
+      for (int j=0;j<1001;j++) {
+        fill(dist[i][j], dist[i][j] + 1001, -1);
+      }
+    }
+    cin >> N >> M;
+    for (int i=0;i<N;i++) {
+      string line;
+      cin >> line;
+      for (int j=0;j<M;j++) {
+        map[i][j] = line.at(j) - '0';
+      }
+    }
+    queue<tuple<int, int, int> > Q;
+    dist[0][0][0] = 1;
+    Q.push(make_tuple(0, 0, 0));
+    while (!Q.empty()) {
+      tuple<int, int, int> top = Q.front(); Q.pop();
+      int x = get<0>(top);
+      int y = get<1>(top);
+      int broken_wall_count = get<2>(top);
+      for (int i=0;i<4;i++) {
+        int nx = x + dx[i];
+        int ny = y + dy[i];
+        if (0 <= nx && nx < M && 0 <= ny && ny < N) {
+          bool is_wall = map[ny][nx] == 1;
+          int next_wall_count = is_wall ? broken_wall_count + 1 : broken_wall_count;
+          if (next_wall_count <= MAX_BREAKABLE_WALL && dist[next_wall_count][ny][nx] == -1) {
+            dist[next_wall_count][ny][nx] = dist[broken_wall_count][y][x] + 1;
+            Q.push(make_tuple(nx, ny, next_wall_count));
+          }
+        }
+      }
+    }
+    int result = (dist[0][N-1][M-1] == -1 && dist[1][N-1][M-1] == -1)
+      ? -1
+      : (dist[0][N-1][M-1] == -1 && dist[1][N-1][M-1] != -1)
+        ? dist[1][N-1][M-1]
+        : (dist[0][N-1][M-1] != -1 && dist[1][N-1][M-1] == -1)
+          ? dist[0][N-1][M-1]
+          : min(dist[0][N-1][M-1], dist[1][N-1][M-1]);
+    cout << result;
+
+    return 0;
+}
diff --git a/201902654/2230.cpp b/201902654/2230.cpp
new file mode 100644
index 0000000..86c6e6f
--- /dev/null
+++ b/201902654/2230.cpp
@@ -0,0 +1,29 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int N, M;
+    cin >> N >> M;
+    int arr[N];
+    for (int i=0;i<N;i++) {
+      cin >> arr[i];
+    }
+    sort(arr, arr + N);
+    int end = 0;
+    int result = __INT_MAX__;
+    for (int start=0;start<N;start++) {
+      while (end < N) {
+        if (abs(arr[start] - arr[end]) >= M) {
+          result = min(result, abs(arr[start] - arr[end]));
+          break;
+        }
+        end++;
+      }
+    }
+    cout << result;
+
+    return 0;
+}
diff --git a/201902654/2468.cpp b/201902654/2468.cpp
new file mode 100644
index 0000000..6b71deb
--- /dev/null
+++ b/201902654/2468.cpp
@@ -0,0 +1,56 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+#include <limits>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int heights[101][101];
+bool is_visit[101][101];
+int N;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> N;
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<N;x++) {
+        cin >> heights[y][x];
+      }
+    }
+    int result = INT_MIN;
+    for (int rain=0;rain<101;rain++) {
+      int count = 0;
+      for (int i=0;i<N;i++) fill(is_visit[i], is_visit[i]+N+1, false);
+      for (int y=0;y<N;y++) {
+        for (int x=0;x<N;x++) {
+          if (!is_visit[y][x] && heights[y][x] > rain) {
+            count++;
+            queue<pair<int, int> > Q;
+            Q.push(make_pair(x, y));
+            is_visit[y][x] = true;
+            while (!Q.empty()) {
+              pair<int, int> top = Q.front(); Q.pop();
+              for (int i=0;i<4;i++) {
+                int nx = top.X + dx[i];
+                int ny = top.Y + dy[i];
+                if (0 <= nx && nx < N && 0 <= ny && ny < N && !is_visit[ny][nx] && heights[ny][nx] > rain) {
+                  is_visit[ny][nx] = true;
+                  Q.push(make_pair(nx, ny));
+                }
+              }
+            }
+          }
+        }
+      }
+      result = max(result, count);
+    }
+    cout << result;
+    return 0;
+}
diff --git a/201902654/2493.cpp b/201902654/2493.cpp
new file mode 100644
index 0000000..ca43850
--- /dev/null
+++ b/201902654/2493.cpp
@@ -0,0 +1,33 @@
+#include <string>
+#include <algorithm>
+#include <stack>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int N;
+    cin >> N;
+    int arr[N];
+    int result[N];
+    fill(result, result+N, 0);
+    stack<pair<int, int> > stack;
+    for (int i=0;i<N;i++) {
+      cin >> arr[i];
+    }
+    for (int i=N-1;i>=0;i--) {
+      while (!stack.empty() && stack.top().second < arr[i]) {
+        result[stack.top().first] = i + 1;
+        stack.pop();
+      }
+      stack.push(make_pair(i, arr[i]));
+    }
+
+    for (int iter : result) {
+      cout << iter << ' ';
+    }
+    return 0;
+}
diff --git a/201902654/2504.cpp b/201902654/2504.cpp
new file mode 100644
index 0000000..b5380c9
--- /dev/null
+++ b/201902654/2504.cpp
@@ -0,0 +1,55 @@
+#include <string>
+#include <stack>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    string line;
+    cin >> line;
+    stack<char> S;
+    int temp = 1;
+    int result = 0;
+    bool is_error = false;
+    for (int i=0;i<line.size();i++) {
+      char ch = line.at(i);
+      if (ch == '(') {
+        S.push(ch);
+        temp *= 2;
+      }
+      if (ch == '[') {
+        S.push(ch);
+        temp *= 3;
+      }
+      if (ch == ')') {
+        if (S.empty()) {
+          is_error = true;
+          break;
+        } else if (S.top() == '(') {
+          if (line.at(i-1) == '(') {
+            result += temp;
+          }
+          temp /= 2;
+          S.pop();
+        }
+      }
+      if (ch == ']') {
+        if (S.empty()) {
+          is_error = true;
+          break;
+        } else if (S.top() == '[') {
+          if (line.at(i-1) == '[') {
+            result += temp;
+          }
+          temp /= 3;
+          S.pop();
+        }
+      }
+    }
+    cout << ((!S.empty() || is_error) ? 0 : result);
+
+    return 0;
+}
diff --git a/201902654/2573.cpp b/201902654/2573.cpp
new file mode 100644
index 0000000..9cab3bd
--- /dev/null
+++ b/201902654/2573.cpp
@@ -0,0 +1,87 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int board[301][301];
+bool is_visit[301][301];
+int N, M;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> N >> M;
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<M;x++) {
+        cin >> board[y][x];
+      }
+    }
+    int time = 0;
+    bool is_ice_exist = false;
+    while (true) {
+      time++;
+      int new_board[301][301];
+      for (int y=0;y<301;y++) {
+        fill(new_board[y], new_board[y]+301, 0);
+        fill(is_visit[y], is_visit[y]+301, 0);
+      }
+      is_ice_exist = false;
+      for (int y=0;y<N;y++) {
+        for (int x=0;x<M;x++) {
+          if (board[y][x] > 0) {
+            is_ice_exist = true;
+            int count = 0;
+            for (int i=0;i<4;i++) {
+              int nx = x + dx[i];
+              int ny = y + dy[i];
+              if (board[ny][nx] == 0) {
+                count++;
+              }
+            }
+            new_board[y][x] = max(0, board[y][x] - count);
+          }
+        }
+      }
+      for (int i=0;i<301;i++) {
+        for (int j=0;j<301;j++) {
+          board[i][j] = new_board[i][j];
+        }
+      }
+      queue<pair<int, int> > Q;
+      int area = 0;
+      for (int y=0;y<N;y++) {
+        for (int x=0;x<M;x++) {
+          if (board[y][x] > 0 && !is_visit[y][x]) {
+            area++;
+            Q.push(make_pair(x, y));
+            is_visit[y][x] = true;
+            while (!Q.empty()) {
+              pair<int, int> top = Q.front(); Q.pop();
+              for (int i=0;i<4;i++) {
+                int nx = top.X + dx[i];
+                int ny = top.Y + dy[i];
+                if (!is_visit[ny][nx] && board[ny][nx] != 0) {
+                  is_visit[ny][nx] = true;
+                  Q.push(make_pair(nx, ny));
+                }
+              }
+            }
+          }
+        }
+      }
+      if (area > 1) {
+        cout << time;
+        break;
+      }
+      if (is_ice_exist == false) {
+        break;
+      }
+    }
+    if (is_ice_exist == false) {
+      cout << 0;
+    }
+
+    return 0;
+}
diff --git a/201902654/2577.cpp b/201902654/2577.cpp
new file mode 100644
index 0000000..3fea25d
--- /dev/null
+++ b/201902654/2577.cpp
@@ -0,0 +1,25 @@
+#include <string>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int A, B, C;
+    cin >> A >> B >> C;
+    int result = A * B * C;
+    int count[10];
+    fill(count, count + 10, 0);
+    string text;
+    text = to_string(result);
+    for (char ch : text) {
+      count[ch - '0']++;
+    }
+    for (int iter : count) {
+      cout << iter << '\n';
+    }
+
+    return 0;
+}
diff --git a/201902654/2583.cpp b/201902654/2583.cpp
new file mode 100644
index 0000000..b315e02
--- /dev/null
+++ b/201902654/2583.cpp
@@ -0,0 +1,63 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int board[101][101];
+bool is_visit[101][101];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int count = 0;
+    vector<int> arr;
+    int M, N, K;
+    queue<pair<int, int> > Q;
+    cin >> M >> N >> K;
+    for (int i=0;i<K;i++) {
+      int start_x, start_y, end_x, end_y;
+      cin >> start_x >> start_y >> end_x >> end_y;
+      for (int y=start_y;y<end_y;y++) {
+        for (int x=start_x;x<end_x;x++) {
+          board[y][x] = 1;
+        }
+      }
+    }
+    for (int y=0;y<M;y++) {
+      for (int x=0;x<N;x++) {
+        if (board[y][x] == 0 && !is_visit[y][x]) {
+          count++;
+          int area = 1;
+          is_visit[y][x] = true;
+          Q.push(make_pair(x, y));
+          while (!Q.empty()) {
+            pair<int, int> top = Q.front(); Q.pop();
+            for (int i=0;i<4;i++) {
+              int nx = top.X + dx[i];
+              int ny = top.Y + dy[i];
+              if (0 <= nx && nx < N && 0 <= ny && ny < M && board[ny][nx] == 0 && !is_visit[ny][nx]) {
+                is_visit[ny][nx] = true;
+                area++;
+                Q.push(make_pair(nx, ny));
+              }
+            }
+          }
+          arr.push_back(area);
+        }
+      }
+    }
+    sort(arr.begin(), arr.end());
+    cout << count << '\n';
+    for (int iter : arr) {
+      cout << iter << ' ';
+    }
+
+    return 0;
+}
diff --git a/201902654/2630.cpp b/201902654/2630.cpp
new file mode 100644
index 0000000..da39ceb
--- /dev/null
+++ b/201902654/2630.cpp
@@ -0,0 +1,42 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int board[128][128];
+int N;
+int counts[2];
+
+void recursion(int N, int init_x, int init_y) {
+  int comp = board[init_y][init_x];
+  bool is_same = true;
+  for (int y = init_y; y < N + init_y; y++) {
+    for (int x = init_x; x < N + init_x; x++) {
+      if (comp != board[y][x]) is_same = false;
+    }
+  }
+  if (is_same) {
+    counts[comp]++;
+  } else {
+    int w = N / 2;
+    recursion(N/2, init_x, init_y);
+    recursion(N/2, init_x + w, init_y);
+    recursion(N/2, init_x, init_y + w);
+    recursion(N/2, init_x + w, init_y + w);
+  }
+}
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> N;
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<N;x++) {
+        cin >> board[y][x];
+      }
+    }
+    recursion(N, 0, 0);
+    cout << counts[0] << '\n';
+    cout << counts[1] << '\n';
+
+    return 0;
+}
diff --git a/201902654/2667.cpp b/201902654/2667.cpp
new file mode 100644
index 0000000..9c5416b
--- /dev/null
+++ b/201902654/2667.cpp
@@ -0,0 +1,61 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int map[26][26];
+bool is_visit[26][26];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int N;
+    cin >> N;
+    for (int i=0;i<N;i++) {
+      string line;
+      cin >> line;
+      for (int j=0;j<N;j++) {
+        map[i][j] = line.at(j) - '0';
+      }
+    }
+    int count_result = 0;
+    vector<int> area_result;
+    for (int y=0;y<N;y++) {
+      for (int x=0;x<N;x++) {
+        if (!is_visit[y][x] && map[y][x] == 1) {
+          int area = 1;
+          count_result++;
+          queue<pair<int, int> > Q;
+          Q.push(make_pair(x, y));
+          is_visit[y][x] = true;
+          while (!Q.empty()) {
+            pair<int, int> top = Q.front(); Q.pop();
+            for (int i=0;i<4;i++) {
+              int nx = top.X + dx[i];
+              int ny = top.Y + dy[i];
+              if (0 <= nx && nx < N && 0 <= ny && ny < N && !is_visit[ny][nx] && map[ny][nx] == 1) {
+                area++;
+                is_visit[ny][nx] = true;
+                Q.push(make_pair(nx, ny));
+              }
+            }
+          }
+          area_result.push_back(area);
+        }
+      }
+    }
+    sort(area_result.begin(), area_result.end());
+    cout << count_result << '\n';
+    for (int iter : area_result) {
+      cout << iter << '\n';
+    }
+
+    return 0;
+}
diff --git a/201902654/32068.cpp b/201902654/32068.cpp
new file mode 100644
index 0000000..9d6bc62
--- /dev/null
+++ b/201902654/32068.cpp
@@ -0,0 +1,26 @@
+#include <string>
+#include <vector>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int T;
+    cin >> T;
+    for (int i=0;i<T;i++) {
+      int L, S, R;
+      cin >> L >> R >> S;
+
+      int result = min((S - L) * 2 + 1, (R - S) * 2);
+      if (L == S || S == R) {
+        cout << 1 << '\n';
+      } else {
+        cout << result << '\n';
+      }
+    }
+
+    return 0;
+}
diff --git a/201902654/3273.cpp b/201902654/3273.cpp
new file mode 100644
index 0000000..33faef8
--- /dev/null
+++ b/201902654/3273.cpp
@@ -0,0 +1,34 @@
+#include <iostream>
+#include <vector>
+#include <string>
+
+using namespace std;
+
+int main(void) {
+  ios::sync_with_stdio(0);
+  cin.tie(0);
+
+  int n;
+  cin >> n;
+  vector<int> arr(2000001, 0);
+  for (int i=0;i<n;++i) {
+    int input;
+    cin >> input;
+    ++arr[input];
+  }
+  int x;
+  cin >> x;
+
+  int result = 0;
+  if (x % 2 == 0) {
+    for (int i=1;i<x/2;++i){
+      result = result + arr[i] * arr[x - i];
+    }
+    result = result + (arr[x/2] * (arr[x/2] - 1) / 2);
+  } else {
+    for (int i=1;i<=x/2;++i){
+      result = result + arr[i] * arr[x - i];
+    }
+  }
+  cout << result;
+}
diff --git a/201902654/3986.cpp b/201902654/3986.cpp
new file mode 100644
index 0000000..d5aa311
--- /dev/null
+++ b/201902654/3986.cpp
@@ -0,0 +1,31 @@
+#include <string>
+#include <stack>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int N;
+    cin >> N;
+    int result = 0;
+    for (int i=0;i<N;i++) {
+      stack<char> S;
+      string line;
+      cin >> line;
+      for (char ch : line) {
+        if (S.size() > 0 && S.top() == ch) {
+          S.pop();
+        } else {
+          S.push(ch);
+        }
+      }
+      if (S.size() == 0) {
+        result++;
+      }
+    }
+    cout << result;
+    return 0;
+}
diff --git a/201902654/4179.cpp b/201902654/4179.cpp
new file mode 100644
index 0000000..22c3c4b
--- /dev/null
+++ b/201902654/4179.cpp
@@ -0,0 +1,86 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int board[1001][1001];
+int fire_time[1001][1001];
+int j_time[1001][1001];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    for (int i=0;i<1001;i++) {
+      fill(fire_time[i], fire_time[i] + 1001, -1);
+      fill(j_time[i], j_time[i] + 1001, -1);
+    }
+
+    int R, C;
+    int result = __INT_MAX__;
+    pair<int, int> j_location, fire_location;
+    queue<pair<int, int> > Q;
+    cin >> R >> C;
+    for (int i=0;i<R;i++) {
+      string line;
+      cin >> line;
+      for (int j=0;j<C;j++) {
+        if (line.at(j) == '#') {
+          board[i][j] = -1;
+        }
+        if (line.at(j) == 'J') {
+          j_location = make_pair(j, i);
+          j_time[i][j] = 0;
+        }
+        if (line.at(j) == 'F') {
+          fire_location = make_pair(j, i);
+          fire_time[i][j] = 0;
+          Q.push(fire_location);
+        }
+      }
+    }
+
+    while (!Q.empty()) {
+      pair<int, int> top = Q.front(); Q.pop();
+      for (int i=0;i<4;i++) {
+        int nx = top.X + dx[i];
+        int ny = top.Y + dy[i];
+        if (0 <= nx && nx < C && 0 <= ny && ny < R && board[ny][nx] != -1 && fire_time[ny][nx] == -1) {
+          fire_time[ny][nx] = fire_time[top.Y][top.X] + 1;
+          Q.push(make_pair(nx, ny));
+        }
+      }
+    }
+
+    Q.push(j_location);
+    while (!Q.empty()) {
+      pair<int, int> top = Q.front(); Q.pop();
+      if (top.X == 0 || top.X == C - 1 || top.Y == 0 || top.Y == R - 1) {
+        result = min(result, j_time[top.Y][top.X] + 1);
+      }
+      for (int i=0;i<4;i++) {
+        int nx = top.X + dx[i];
+        int ny = top.Y + dy[i];
+        if (0 <= nx && nx < C && 0 <= ny && ny < R && board[ny][nx] != -1 && j_time[ny][nx] == -1 && (fire_time[ny][nx] == -1 || j_time[top.Y][top.X] + 1 < fire_time[ny][nx])) {
+          j_time[ny][nx] = j_time[top.Y][top.X] + 1;
+          Q.push(make_pair(nx, ny));
+        }
+      }
+    }
+
+    if (result == __INT_MAX__) {
+      cout << "IMPOSSIBLE";
+    } else {
+      cout << result;
+    }
+
+    return 0;
+}
+
diff --git a/201902654/4949.cpp b/201902654/4949.cpp
new file mode 100644
index 0000000..9cb0e6a
--- /dev/null
+++ b/201902654/4949.cpp
@@ -0,0 +1,46 @@
+#include <string>
+#include <stack>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    string line;
+    while (true) {
+      stack<char> S;
+      bool is_error = false;
+      getline(cin, line);
+      if (line == ".") {
+        break;
+      }
+      for (char ch : line) {
+        if (ch == '(') {
+          S.push('(');
+        }
+        if (ch == ')') {
+          if (S.size() == 0 || S.top() != '(') {
+            is_error = true;
+            break;
+          } else {
+            S.pop();
+          }
+        }
+        if (ch == '[') {
+          S.push('[');
+        }
+        if (ch == ']') {
+          if (S.size() == 0 || S.top() != '[') {
+            is_error = true;
+            break;
+          } else {
+            S.pop();
+          }
+        }
+      }
+      cout << ((S.size() == 0 && !is_error) ? "yes" : "no") << '\n';
+
+    }
+    return 0;
+}
diff --git a/201902654/5014.cpp b/201902654/5014.cpp
new file mode 100644
index 0000000..8959cac
--- /dev/null
+++ b/201902654/5014.cpp
@@ -0,0 +1,42 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int F, S, G, U, D;
+int button_count[1000001];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> F >> S >> G >> U >> D;
+    fill(button_count, button_count+F+1, -1);
+    queue<int> Q;
+    button_count[S] = 0;
+    Q.push(S);
+    while (!Q.empty()) {
+      int top = Q.front(); Q.pop();
+      if (top + U <= F && button_count[top + U] == -1) {
+        button_count[top + U] = button_count[top] + 1;
+        Q.push(top + U);
+      }
+      if (top - D > 0 && button_count[top - D] == -1) {
+        button_count[top - D] = button_count[top] + 1;
+        Q.push(top - D);
+      }
+    }
+    if (button_count[G] == -1) {
+      cout << "use the stairs";
+    } else {
+      cout << button_count[G];
+    }
+
+    return 0;
+}
diff --git a/201902654/5397.cpp b/201902654/5397.cpp
new file mode 100644
index 0000000..5ee2306
--- /dev/null
+++ b/201902654/5397.cpp
@@ -0,0 +1,44 @@
+#include <string>
+#include <list>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int test_case;
+    cin >> test_case;
+    for (int i=0;i<test_case;++i){
+      string input;
+      list<char> L;
+      auto cursor = L.end();
+      cin >> input;
+
+      for (char ch : input) {
+        if (ch == '<') {
+          if (cursor != L.begin()) {
+            cursor--;
+          }
+        } else if (ch == '>') {
+          if (cursor != L.end()) {
+            cursor++;
+          }
+        } else if (ch == '-') {
+          if (cursor != L.begin()) {
+            cursor--;
+            cursor = L.erase(cursor);
+          }
+        } else {
+          L.insert(cursor, ch);
+        }
+      }
+
+      for (char ch : L) {
+        cout << ch;
+      }
+      cout << '\n';
+    }
+
+    return 0;
+}
diff --git a/201902654/5427.cpp b/201902654/5427.cpp
new file mode 100644
index 0000000..84a9ce3
--- /dev/null
+++ b/201902654/5427.cpp
@@ -0,0 +1,87 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int board[1001][1001];
+int fire_time[1001][1001];
+int human_time[1001][1001];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int T;
+    cin >> T;
+    for (int t=0;t<T;t++) {
+      for (int i=0;i<1001;i++) {
+        fill(board[i], board[i] + 1001, 0);
+        fill(fire_time[i], fire_time[i] + 1001, -1);
+        fill(human_time[i], human_time[i] + 1001, -1);
+      }
+      int result = -1;
+      pair<int, int> human_position;
+      queue<pair<int, int> > Q;
+      int w, h;
+      cin >> w >> h;
+      for (int y=0;y<h;y++) {
+        string line;
+        cin >> line;
+        for (int x=0;x<w;x++) {
+          char ch = line.at(x);
+          if (ch == '#') {
+            board[y][x] = 1;
+          }
+          if (ch == '@') {
+            human_position = make_pair(x, y);
+            human_time[y][x] = 0;
+          }
+          if (ch == '*') {
+            Q.push(make_pair(x, y));
+            fire_time[y][x] = 0;
+          }
+        }
+      }
+      while (!Q.empty()) {
+        pair<int, int> top = Q.front(); Q.pop();
+        for (int i=0;i<4;i++) {
+          int nx = top.X + dx[i];
+          int ny = top.Y + dy[i];
+          if (0 <= nx && nx < w && 0 <= ny && ny < h && board[ny][nx] == 0 && fire_time[ny][nx] == -1) {
+            fire_time[ny][nx] = fire_time[top.Y][top.X] + 1;
+            Q.push(make_pair(nx, ny));
+          }
+        }
+      }
+      Q.push(human_position);
+      while (!Q.empty()) {
+        pair<int, int> top = Q.front(); Q.pop();
+        if (top.X == 0 || top.X == w - 1 || top.Y == 0 || top.Y == h - 1) {
+          result = human_time[top.Y][top.X] + 1;
+          break;
+        }
+        for (int i=0;i<4;i++) {
+          int nx = top.X + dx[i];
+          int ny = top.Y + dy[i];
+          if (0 <= nx && nx < w && 0 <= ny && ny < h && board[ny][nx] == 0 && human_time[ny][nx] == -1 && (fire_time[ny][nx] == -1 || fire_time[ny][nx] > human_time[top.Y][top.X] + 1)) {
+            human_time[ny][nx] = human_time[top.Y][top.X] + 1;
+            Q.push(make_pair(nx, ny));
+          }
+        }
+      }
+      if (result == -1) {
+        cout << "IMPOSSIBLE" << '\n';
+      } else {
+        cout << result << '\n';
+      }
+    }
+
+    return 0;
+}
diff --git a/201902654/5430.cpp b/201902654/5430.cpp
new file mode 100644
index 0000000..d380d71
--- /dev/null
+++ b/201902654/5430.cpp
@@ -0,0 +1,73 @@
+#include <string>
+#include <deque>
+#include <iostream>
+
+using namespace std;
+
+deque<int> tokenize(string s, string del = ",")
+{
+    deque<int> result;
+    int start, end = -1 * del.size();
+    if (s.size() > 0) {
+      do {
+          start = end + del.size();
+          end = s.find(del, start);
+          result.push_back(stoi(s.substr(start, end - start)));
+      } while (end != -1);
+    }
+
+    return result;
+}
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int T;
+    cin >> T;
+    for (int i=0;i<T;i++) {
+      string commands;
+      int n;
+      string arr;
+      cin >> commands;
+      cin >> n;
+      getline(cin >> ws, arr);
+      deque<int> D = tokenize(arr.substr(1, arr.size() - 2), ",");
+      bool is_reversed = false;
+      bool is_error = false;
+      // cout << D.size() << '\n';
+      for (char command : commands) {
+        if (command == 'R') {
+          is_reversed = !is_reversed;
+        } else {
+          if (D.size() == 0) {
+            cout << "error" << '\n';
+            is_error = true;
+            break;
+          }
+          if (is_reversed) {
+            D.pop_back();
+          } else {
+            D.pop_front();
+          }
+        }
+      }
+      if (!is_error) {
+        cout << '[';
+        while (!D.empty()) {
+          if (is_reversed) {
+            cout << D.back();
+            D.pop_back();
+          } else {
+            cout << D.front();
+            D.pop_front();
+          }
+          if (!D.empty()) {
+            cout << ',';
+          }
+        }
+        cout << ']' << '\n';
+      }
+    }
+
+    return 0;
+}
diff --git a/201902654/6198.cpp b/201902654/6198.cpp
new file mode 100644
index 0000000..b428257
--- /dev/null
+++ b/201902654/6198.cpp
@@ -0,0 +1,34 @@
+#include <string>
+#include <stack>
+#include <algorithm>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int N;
+    cin >> N;
+    int arr[N+1], result[N];
+    stack<pair<int, int> > stack;
+    fill(result, result + N, 0);
+    for (int i=0;i<N;i++) {
+      cin >> arr[i];
+    }
+    arr[N] = 1000000000;
+    for (int i=0;i<N+1;i++) {
+      while (!stack.empty() && stack.top().second <= arr[i]) {
+        result[stack.top().first] = i - stack.top().first - 1;
+        stack.pop();
+      }
+      stack.push(make_pair(i, arr[i]));
+    }
+    long value = 0;
+    for (int iter : result) {
+      value = value + iter;
+    }
+    cout << value;
+
+    return 0;
+}
diff --git a/201902654/6593.cpp b/201902654/6593.cpp
new file mode 100644
index 0000000..50710fd
--- /dev/null
+++ b/201902654/6593.cpp
@@ -0,0 +1,75 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+#include <tuple>
+
+using namespace std;
+
+int dx[6] = {0, 0, 1, -1, 0, 0};
+int dy[6] = {1, -1, 0, 0, 0, 0};
+int dz[6] = {0, 0, 0, 0, 1, -1};
+int L, R, C;
+int building[31][31][31];
+int count_minutes[31][31][31];
+tuple<int, int, int> s_position;
+tuple<int, int, int> e_position;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    while (true) {
+      cin >> L >> R >> C;
+      if (L == 0 && R == 0 && C == 0) {
+        break;
+      }
+      for (int z=0;z<L;z++) {
+        for (int y=0;y<R;y++) {
+          fill(count_minutes[z][y], count_minutes[z][y]+C+1, -1);
+          fill(building[z][y], building[z][y]+C+1, 0);
+        }
+      }
+      for (int z=0;z<L;z++) {
+        for (int y=0;y<R;y++) {
+          string line;
+          cin >> line;
+          for (int x=0;x<C;x++) {
+            if (line.at(x) == 'S') {
+              s_position = make_tuple(x, y, z);
+            }
+            if (line.at(x) == 'E') {
+              e_position = make_tuple(x, y, z);
+            }
+            if (line.at(x) == '#') {
+              building[z][y][x] = 1;
+            }
+          }
+        }
+      }
+      queue<tuple<int, int, int> > Q;
+      Q.push(s_position);
+      count_minutes[get<2>(s_position)][get<1>(s_position)][get<0>(s_position)] = 0;
+      while (!Q.empty()) {
+        tuple<int, int, int> top = Q.front(); Q.pop();
+        for (int i=0;i<6;i++) {
+          int nx = get<0>(top) + dx[i];
+          int ny = get<1>(top) + dy[i];
+          int nz = get<2>(top) + dz[i];
+
+          if (0 <= nx && nx < C && 0 <= ny && ny < R && 0 <= nz && nz < L && building[nz][ny][nx] == 0 && count_minutes[nz][ny][nx] == -1) {
+            count_minutes[nz][ny][nx] = count_minutes[get<2>(top)][get<1>(top)][get<0>(top)] + 1;
+            Q.push(make_tuple(nx, ny, nz));
+          }
+        }
+      }
+      if (count_minutes[get<2>(e_position)][get<1>(e_position)][get<0>(e_position)] == -1) {
+        cout << "Trapped!" << '\n';
+      } else {
+        cout << "Escaped in " << count_minutes[get<2>(e_position)][get<1>(e_position)][get<0>(e_position)] << " minute(s)." << '\n';
+      }
+    }
+
+    return 0;
+}
diff --git a/201902654/7562.cpp b/201902654/7562.cpp
new file mode 100644
index 0000000..6d48d73
--- /dev/null
+++ b/201902654/7562.cpp
@@ -0,0 +1,52 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[8] = {1, 2, 2, 1, -1, -2, -2, -1};
+int dy[8] = {-2, -1, 1, 2, 2, 1, -1, -2};
+int moving[301][301];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int T;
+    cin >> T;
+    for (int t=0;t<T;t++) {
+      for (int i=0;i<301;i++) fill(moving[i], moving[i] + 301, -1);
+      int l, x, y;
+      int result = 0;
+      pair<int, int> knight_position, dest_position;
+      queue<pair<int, int> > Q;
+      cin >> l;
+      cin >> x >> y;
+      knight_position = make_pair(x, y);
+      moving[y][x] = 0;
+      Q.push(make_pair(x, y));
+      cin >> x >> y;
+      dest_position = make_pair(x, y);
+
+      while (!Q.empty()) {
+        pair<int, int> top = Q.front(); Q.pop();
+        if (top == dest_position) {
+          break;
+        }
+        for (int i=0;i<8;i++) {
+          int nx = top.X + dx[i];
+          int ny = top.Y + dy[i];
+          if (0 <= nx && nx < l && 0 <= ny && ny < l && moving[ny][nx] == -1) {
+            moving[ny][nx] = moving[top.Y][top.X] + 1;
+            Q.push(make_pair(nx, ny));
+          }
+        }
+      }
+      cout << moving[dest_position.Y][dest_position.X] << '\n';
+    }
+
+    return 0;
+}
diff --git a/201902654/7569.cpp b/201902654/7569.cpp
new file mode 100644
index 0000000..c86a0a4
--- /dev/null
+++ b/201902654/7569.cpp
@@ -0,0 +1,68 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+
+int dx[6] = {0, 0, 1, -1, 0, 0};
+int dy[6] = {1, -1, 0, 0, 0, 0};
+int dz[6] = {0, 0, 0, 0, 1, -1};
+int days[101][101][101];
+int boards[101][101][101];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    for (int i=0;i<101;i++) {
+      for (int j=0;j<101;j++) {
+        fill(days[i][j], days[i][j]+101, -1);
+      }
+    }
+
+    int M, N, H;
+    queue<tuple<int, int, int> > Q;
+    cin >> M >> N >> H;
+    for (int h=0;h<H;h++) {
+      for (int i=0;i<N;i++) {
+        for (int j=0;j<M;j++) {
+          cin >> boards[h][i][j];
+          if (boards[h][i][j] == 1) {
+            Q.push(make_tuple(j, i, h));
+            days[h][i][j] = 0;
+          }
+        }
+      }
+    }
+    while (!Q.empty()) {
+      tuple<int, int, int> top = Q.front(); Q.pop();
+      for (int i=0;i<6;i++) {
+        int nx = get<0>(top) + dx[i];
+        int ny = get<1>(top) + dy[i];
+        int nz = get<2>(top) + dz[i];
+        if (0 <= nx && nx < M && 0 <= ny && ny < N && 0 <= nz && nz < H && boards[nz][ny][nx] != -1 && days[nz][ny][nx] == -1) {
+          days[nz][ny][nx] = days[get<2>(top)][get<1>(top)][get<0>(top)] + 1;
+          Q.push(make_tuple(nx, ny, nz));
+        }
+      }
+    }
+    int result = 0;
+    for (int h=0;h<H;h++) {
+      for (int i=0;i<N;i++) {
+        for (int j=0;j<M;j++) {
+          if (boards[h][i][j] != -1 && days[h][i][j] == -1) {
+            cout << -1;
+            return 0;
+          } else if (boards[h][i][j] != -1) {
+            result = max(result, days[h][i][j]);
+          }
+        }
+      }
+    }
+    cout << result;
+
+
+    return 0;
+}
diff --git a/201902654/7576.cpp b/201902654/7576.cpp
new file mode 100644
index 0000000..e4914b5
--- /dev/null
+++ b/201902654/7576.cpp
@@ -0,0 +1,61 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <algorithm>
+
+using namespace std;
+#define X first
+#define Y second
+int dx[4] = {0, 0, 1, -1};
+int dy[4] = {1, -1, 0, 0};
+int days[1001][1001];
+int boards[1001][1001];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    for (int i=0;i<1001;i++) {
+      fill(days[i], days[i]+1001, -1);
+    }
+
+    int M, N;
+    queue<pair<int, int> > Q;
+    cin >> M >> N;
+    for (int i=0;i<N;i++) {
+      for (int j=0;j<M;j++) {
+        cin >> boards[i][j];
+        if (boards[i][j] == 1) {
+          Q.push(make_pair(j, i));
+          days[i][j] = 0;
+        }
+      }
+    }
+    while (!Q.empty()) {
+      pair<int, int> top = Q.front(); Q.pop();
+      for (int i=0;i<4;i++) {
+        int nx = top.X + dx[i];
+        int ny = top.Y + dy[i];
+        if (0 <= nx && nx < M && 0 <= ny && ny < N && boards[ny][nx] != -1 && days[ny][nx] == -1) {
+          days[ny][nx] = days[top.Y][top.X] + 1;
+          Q.push(make_pair(nx, ny));
+        }
+      }
+    }
+    int result = 0;
+    for (int i=0;i<N;i++) {
+      for (int j=0;j<M;j++) {
+        if (boards[i][j] != -1 && days[i][j] == -1) {
+          cout << -1;
+          return 0;
+        } else if (boards[i][j] != -1) {
+          result = max(result, days[i][j]);
+        }
+      }
+    }
+    cout << result;
+
+
+    return 0;
+}
diff --git a/201902654/9012.cpp b/201902654/9012.cpp
new file mode 100644
index 0000000..8d75419
--- /dev/null
+++ b/201902654/9012.cpp
@@ -0,0 +1,35 @@
+#include <string>
+#include <stack>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+
+    int T;
+    cin >> T;
+    for (int i=0;i<T;i++) {
+      stack<char> S;
+      bool is_error = false;
+      string line;
+      cin >> line;
+
+      for (char ch : line) {
+        if (ch == '(') {
+          S.push(ch);
+        } else {
+          if (S.size() == 0 || S.top() != '(') {
+            is_error = true;
+            break;
+          } else {
+            S.pop();
+          }
+        }
+      }
+      cout << ((S.size() == 0 && !is_error) ? "YES" : "NO") << '\n';
+    }
+
+    return 0;
+}
diff --git a/201902654/9466.cpp b/201902654/9466.cpp
new file mode 100644
index 0000000..dec77d9
--- /dev/null
+++ b/201902654/9466.cpp
@@ -0,0 +1,53 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+int T;
+int select_num[100001], connecting[100001];
+bool is_visit[100001];
+
+int main() {
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cin >> T;
+    for (int t=0;t<T;t++) {
+      fill(select_num, select_num+100001, 0);
+      fill(connecting, connecting+100001, 0);
+      fill(is_visit, is_visit+100001, 0);
+      int n;
+      queue<int> Q;
+      cin >> n;
+      for (int i=0;i<n;i++) {
+        cin >> select_num[i];
+      }
+      for (int i=0;i<n;i++) {
+        if (connecting[i] == 0 && !is_visit[i]) {
+          Q.push(i);
+          is_visit[i] = true;
+          connecting[i] = i;
+          while (!Q.empty()) {
+            int top = Q.front(); Q.pop();
+            int next = select_num[top] - 1;
+            if (is_visit[next] == true && connecting[next] == i) {
+              connecting[next] = -1;
+              Q.push(next);
+            } else if (is_visit[next] == false) {
+              is_visit[next] = true;
+              connecting[next] = i;
+              Q.push(next);
+            }
+          }
+        }
+      }
+
+      int result = 0;
+      for (int i=0;i<n;i++) {
+        // cout << connecting[i] << ' ';
+        if (connecting[i] == -1) {
+          result++;
+        }
+      }
+      cout << n - result << '\n';
+    }
+
+    return 0;
+}