using System;

public class Program

{

    public static void Main()

    {

        int f=1;

        Console.WriteLine("Hello! Write a number and I'll tell you its factorial");

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

        for (int i = 1; i<=n; i++)

        {

         f *= i;

            }

        Console.WriteLine(n + "!" + " = " + f);

    }

}