using System;

public class Program

{

    public static void Main()

    {

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

        var fact = 1;

        do

        {

        fact = fact * n; //1 * 5 * 4 * 3 * 2

        n--;

        } while (n > 1);

        Console.WriteLine(fact);

    }

}