using System;

public class Program

{

    public static void Main()

    {

        start:

        Console.Clear();

        Console.WriteLine("Which number's factorial would you like to calculate?");

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

        ulong final = 1;

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

        {final *=i;}

        if (num < 66)

            Console.WriteLine("The factorial of the number " + num + " is " + final);

        if (num >=66)

        {Console.WriteLine("Please enter a smaller number you would like to calculate the factorial of.");

        ulong num1 = ulong.Parse(Console.ReadLine());

         ulong final1 = 1;

         for(ulong i = 1; i <= num1; i++)

         {final *=i;}

         Console.WriteLine("The factorial of the number " + num + " is " + final1);

        }

        Console.WriteLine("Would you like to run the program again? y/n");

        string choice = Console.ReadLine();

        if (choice == "y" || choice == "Y")

            goto start;

    }

}