using System;

​

public class Demo

{

    public static void Main(string[] args)

    {

        Func<int, int> xxx = null;

        xxx = n => n <= 1 ? 1 : n * xxx(n - 1);

        for (int m = 1; m < 6; m++)

            Console.WriteLine("m=  {0}  xxx = {1}", m, xxx(m));

    }

}