using System;

public class Program

{

    public static void Main()

    {

        start:

        Console.WriteLine("What number would like to know the factorial of?");

        ulong ans = ulong.Parse(Console.ReadLine());

        if (ans > 100)

        {

            Console.WriteLine("You must enter a number less than 100");

            goto start;

        }

        else

        {

            ulong fact = 1;

            for(ulong i = 1; i<= ans; i++)

            {

                fact *= i;

            }

        Console.WriteLine(ans + "= " + fact);

        }

        Console.WriteLine("Would like to re-enter a number?y/n");

        string choice = Console.ReadLine();

        goto start;

    }

}