using System;

public class Program

{

    public static void Main()

    {

        int n;

        int fact = 1;

        Console.WriteLine("Enter a number: ");

        n = Convert.ToInt32(Console.ReadLine());

        while (n > 1)

        {

        fact = fact * n;

        n = n-1;

        }

        Console.WriteLine("Fact is {0}", fact);

    }

}