Stack Implementation using List

class Stack:
    def __init__(self):
        self.stack = []
    
    def push(self, item):
        """Add an element to the top of stack"""
        self.stack.append(item)
        print(f"Pushed {item} to stack")
    
    def pop(self):
        """Remove and return the top element from stack"""
        if self.is_empty():
            print("Stack is empty! Cannot pop.")
            return None
        else:
            item = self.stack.pop()
            print(f"Popped {item} from stack")
            return item
    
    def peek(self):
        """Return the top element without removing it"""
        if self.is_empty():
            print("Stack is empty!")
            return None
        else:
            return self.stack[-1]
    
    def is_empty(self):
        """Check if stack is empty"""
        return len(self.stack) == 0
    
    def size(self):
        """Return the size of stack"""
        return len(self.stack)
    
    def display(self):
        """Display all elements in stack"""
        if self.is_empty():
            print("Stack is empty!")
        else:
            print("Stack contents (top to bottom):")
            for i in range(len(self.stack) - 1, -1, -1):
                print(f"| {self.stack[i]} |")
            print("+---+")

def main():
    stack = Stack()
    
    while True:
        print("\n--- Stack Operations ---")
        print("1. Push")
        print("2. Pop")
        print("3. Peek")
        print("4. Display")
        print("5. Size")
        print("6. Exit")
        
        choice = input("Enter your choice (1-6): ")
        
        if choice == '1':
            item = input("Enter element to push: ")
            stack.push(item)
        
        elif choice == '2':
            stack.pop()
        
        elif choice == '3':
            top = stack.peek()
            if top is not None:
                print(f"Top element: {top}")
        
        elif choice == '4':
            stack.display()
        
        elif choice == '5':
            print(f"Stack size: {stack.size()}")
        
        elif choice == '6':
            print("Exiting...")
            break
        
        else:
            print("Invalid choice! Please try again.")

if __name__ == "__main__":
    main()