using System;
using System.Numerics;

    class FactorialN
    {
        static void Main()
        {
            Console.WriteLine("Enter n! - from 0 to 100: ");
            int n = int.Parse(Console.ReadLine());

            FactorialCalculation(n);

        }

        private static void FactorialCalculation(int n)
        {
            BigInteger factorial = 1;

            for (int i = 1; i <= n; i++)
            {
                factorial *= i;
            }

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