diff --git a/converters.py b/converters.py
new file mode 100644
index 0000000..23fc2ab
--- /dev/null
+++ b/converters.py
@@ -0,0 +1,21 @@
+from operacao import Operacao
+from decimal import Decimal
+
+def toOperacao(tuple):
+    return Operacao(tuple[0], tuple[1], tuple[2], tuple[3], tuple[4], tuple[5], tuple[6])
+
+def toDateYMD(dataDMY):
+    a = str(dataDMY).split('/')
+    y = a[2]
+    m = a[1]
+    d = a[0]
+    return y + '-' + m + '-' + d
+
+def toDecimal(str):
+    if (',' in str and '.' in str):
+        raise Exception("Número inválido: [" + str + "]. Use vírgula para decimais.")
+    str = str.replace(',', '.')
+    return Decimal(str)
+
+#print(toDateYMD("23/01/2021"))
+#print(toNumber("1.024,68"))
diff --git a/database.py b/database.py
index 31d8581..85d56c4 100644
--- a/database.py
+++ b/database.py
@@ -1,5 +1,6 @@
 # https://docs.python.org/3/library/sqlite3.html
 import sqlite3
+import converters
 
 class Database:
 
@@ -30,5 +31,23 @@ def list(self):
 
         rows = c.fetchall()
 
+        #for r in rows:
+        #    print(r)
+
+        return rows
+
+    def listarPorTicker(self, ticker):
+        con = self.con
+        c = con.cursor()
+
+        c.execute("SELECT * FROM operacao WHERE ticker = ? ORDER BY data", (ticker,))
+
+        rows = c.fetchall()
+
+        i = 0
         for r in rows:
-            print(r)
+            rows[i] = converters.toOperacao(r)
+            #print(rows[i])
+            i+=1
+
+        return rows
diff --git a/leitor.py b/leitor.py
index c085d8d..db46c2c 100644
--- a/leitor.py
+++ b/leitor.py
@@ -1,5 +1,6 @@
 import sys
 import parsers
+from rn import RN
 from operacao import Operacao
 from database import Database
 
@@ -15,10 +16,17 @@
 print("Lendo arquivo " + arquivo + "...")
 print()
 
-f = open(arquivo, "r", encoding="utf-8")
-
-lines = f.readlines()
-#print(*lines)
+lines = None
+try:
+    f = open(arquivo, "r", encoding="UTF-8")
+    lines = f.readlines()
+    #print(*lines)
+except UnicodeDecodeError:
+    f = open(arquivo, "r", encoding="ISO-8859-1")
+    lines = f.readlines()
+except:
+    print("Não foi possível ler o arquivo [" + arquivo + "].")
+    sys.exit(0)
 
 print("Extraindo operações...\n")
 
@@ -45,7 +53,7 @@ def isEmBranco(txt):
     line = line.strip()
     i+=1
 
-    print(str(i).zfill(3), line)
+    print(str(i).zfill(4), line)
 
     if isEmBranco(line):
         continue
@@ -77,21 +85,20 @@ def isEmBranco(txt):
         print("Preço inválido na linha", str(i) + ":", line)
         sys.exit(0)
 
-    operacoes.append(Operacao(data, cv, qtd, ticker, preco, ""))
+    operacoes.append(Operacao(None, data, cv, qtd, ticker, preco, ""))
 
 print()
 print("Leitura do arquivo " + arquivo + " concluída.")
 print()
 
-print("Operações: ")
-print()
+#print("Operações: ")
+#print()
 
-for o in operacoes:
-    print(o)
+#for o in operacoes:
+#    print(o)
 
 print()
 
-db = Database()
-for o in operacoes:
-    db.add(o)
-
+rn = RN(operacoes)
+pm = rn.precoMedio("B3SA3", "C")
+print("Preço médio = " + str(pm))
diff --git a/operacao.py b/operacao.py
index 35bfd84..5224f31 100644
--- a/operacao.py
+++ b/operacao.py
@@ -1,6 +1,7 @@
 class Operacao:
 
-    def __init__(self, data, cv, qtd, ticker, preco, nota):
+    def __init__(self, id, data, cv, qtd, ticker, preco, nota):
+        self.id = id
         self.data = data if isinstance(data, str) else data[0]
         self.cv = cv if isinstance(cv, str) else cv[0]
         self.qtd = qtd if isinstance(qtd, str) else qtd[0]
@@ -9,4 +10,10 @@ def __init__(self, data, cv, qtd, ticker, preco, nota):
         self.nota = nota if isinstance(nota, str) else nota[0]
 
     def __str__(self):
-        return str(self.data) + " " + str(self.cv) + " " + str(self.qtd) + " " + str(self.ticker) + " " + str(self.preco) + " " + str(self.nota)
+        return str(self.id).zfill(4) + " " + str(self.data) + " " + str(self.cv) + " " + str(self.qtd) + " " + str(self.ticker) + " " + str(self.preco) + " " + str(self.nota)
+
+    def isCompra(self):
+        return True if self.cv.upper() == 'C' else False
+
+    def isVenda(self):
+        return True if self.cv.upper() == 'V' else False
diff --git a/rn.py b/rn.py
new file mode 100644
index 0000000..7475e7a
--- /dev/null
+++ b/rn.py
@@ -0,0 +1,27 @@
+from database import Database
+import converters
+
+class RN:
+
+    db = None
+
+    def __init__(self, operacoes):
+        self.db = Database()
+        for o in operacoes:
+            self.db.add(o)
+
+    def precoMedio(self, ticker, cv):
+        db = self.db
+        l = db.listarPorTicker(ticker)
+
+        somatorio = 0
+
+        for o in l:
+            if (o.isCompra() and cv.upper() == 'C'):
+                somatorio += converters.toDecimal(o.preco)
+                print(o)
+            elif (o.isVenda() and cv.upper() == 'V'):
+                somatorio += converters.toDecimal(o.preco)
+                print(o)
+        
+        return round(somatorio / l.__len__(), 2)
diff --git a/teste.txt b/teste.txt
index 1025109..bb66f6a 100644
--- a/teste.txt
+++ b/teste.txt
@@ -1,5 +1,7 @@
 # um comentário
+
+01/02/2021 C 25 B3SA3 50,00    # Clear
+01/03/2021 C 25 B3SA3 51,00    # Clear
 17/03/2021 C 50 B3SA3 52,68    # Clear
 18/03/2021 V 100 LEVE3 19,24   # Mirae
-
 18/03/2021 V 100 LEVE3 19,24   # Mirae