using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Entrer un nombre entier svp");

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

        Console.WriteLine("Factorielle de {0} vaut {1}",n,fact(n));

    }

    public static int fact(int n)

    {

    if(n==0){

    return 1;

    }

    return n*fact(n-1);

    }

}