using System;

public class Program

{

    public static void Main()

    {

        int n = 3;

        int ketQua = TinhGiaiThua(n);

        Console.WriteLine(ketQua);

    }

    public static int TinhGiaiThua(int n)

    {

        int giaiThua = 1;

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

        {

            giaiThua*= i;

        }

        return giaiThua;

    }

}