diff --git a/product_class.py b/product_class.py
index c1b8a56..e07ed0e 100644
--- a/product_class.py
+++ b/product_class.py
@@ -1,5 +1,7 @@
 class product:
-    def __init__(self, name: str, price: float, quantity: int = 1):
+    def __init__(self, name: str, price: float, quantity = 0):
+        assert price >= 0, "Price must be non-negative"
+        assert quantity >= 0, "Quantity must be non-negative"          
         self.name = name
         self.price = price
         self.quantity = quantity
@@ -13,7 +15,8 @@ class product:
 
 
 # Example usage:
-product1 = product("Laptop", 1999.99, 1) 
+
+product1 = product("Laptop", 1999.99, -1) 
 print(product1.display_info())  # Output: Item: Laptop, Price: $1999.99
 print(product1.calculate_total_price())  # Output: 3999996.0001
 product2 = product("Smartphone", 799.99, 3)