Let n be a nonnegative integer. The factorial of n, written n!, is defined by 0!=1, n! =1*2*3*...*n if n >= 1. For example, 4! = 1*2*3*4 = 24. Write a program that prompts the user to enter a nonnegative integer and outputs the factorial of the number.

Output format:

4! = 24

0! = 1

Notes: - You must check if the entered integer is non-negative. If it is negative, keep asking the user to input a non-negative integer. You can use infinite