3、判断

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

namespace jiecheng
{
class jiecheng
{
public int Jc(int num)
{

        return num > 0 ? num *Jc(num - 1):1;  //如果num>0则返回num *Jc(num - 1)，否则返回1
    }
}




class excutejiecheng

{
    static void Main(string[] args)
    {
        jiecheng n = new jiecheng();
        int result = n.Jc(Convert.ToInt16(Console.ReadLine()));
        Console.WriteLine("result is {0}",result);
        Console.ReadKey();
    }
}

}