using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        int factoriel = 1;
        if (n > 0)
        {
            for (int i = 1; i <= n; i++)
            {
                factoriel = factoriel * i;
            }
        }

        Console.WriteLine($"{factoriel}");
    }
}