diff --git a/src/main/java/controller/Controller.java b/src/main/java/controller/Controller.java
index 5441e6f..34137a5 100644
--- a/src/main/java/controller/Controller.java
+++ b/src/main/java/controller/Controller.java
@@ -630,9 +630,14 @@ public String digest(String productId) {
 
     public void addToCart(String productId) {
         if (currentAccount.getRole() == Role.CUSTOMER) {
-            Map<Product,Integer> cart = currentAccount.getCart();
-            cart.put(getAvailableProductById(productId),1);
-            currentAccount.setCart(cart);
+            if (getProductById(productId).getAmount() > 0) {
+                Map<Product,Integer> cart = currentAccount.getCart();
+                cart.put(getAvailableProductById(productId),1);
+                currentAccount.setCart(cart);
+                getProductById(productId).setAmount(getProductById(productId).getAmount() - 1);
+            }
+            else
+                System.out.println("not available");
         }
         else
             System.out.println("invalid command");
diff --git a/src/main/java/view/Menu/GoodMenu.java b/src/main/java/view/Menu/GoodMenu.java
index 118d5dd..11e4a26 100644
--- a/src/main/java/view/Menu/GoodMenu.java
+++ b/src/main/java/view/Menu/GoodMenu.java
@@ -128,8 +128,13 @@ public void show() {
                 System.out.println("Compare Menu");
                 System.out.println("1.back");
                 String input = scanner.nextLine();
-                for (String productAttribute : controller.compare(goodId, input)) {
-                    System.out.println(productAttribute);
+                if (controller.getProductById(input) != null) {
+                    for (String productAttribute : controller.compare(goodId, input)) {
+                        System.out.println(productAttribute);
+                    }
+                }
+                else {
+                    System.out.println("invalid id");
                 }
             }