Python program to calculate Factorial of number

    
        def factorial(n):
            # Base case: If n is 0 or 1, the factorial is 1.
            if n == 0 or n == 1:
                return 1
            else:
                # Recursive case: n! = n * (n-1)!
                # Here, we multiply n by the factorial of (n-1).
                return n * factorial(n-1)

        # Example usage:
        # Get input from the user (assumes the user enters a non-negative integer).
        num = int(input("Enter a non-negative integer: "))

        # Check if the input is negative.
        if num < 0:
            print("Factorial is not defined for negative numbers.")
        else:
            # Calculate the factorial using the factorial function.
            result = factorial(num)

            # Display the result to the user.
            print(f"The factorial of {num} is: {result}")
    

    
        Enter a non-negative integer: 5
        The factorial of 5 is: 120