using System;

//using System.Collections.Generic;

//using System.Text;

namespace digui1

{

    public class Program

    {

       public static void Main()

        {

            int n;

            n = int.Parse(Console.ReadLine());

            Console.WriteLine("{0}!={1}.", n, fun(n));

            Console.ReadLine();

        }

        public static int fun(int n)

        {

            if (n <= 1)

                return 1;

            else

                return n * fun(n - 1);

        }

    }

}