using System;

namespace ConsoleApp3

{

    class Program

    {

        static void Main(string[] args)

        {

            int b = j1();

            Console.WriteLine(b);

            int a = j();

            Console.WriteLine(a);

        }

       /// <summary>

       /// 循环求阶乘

       /// </summary>

       /// <param name="b"></param>

       /// <returns></returns>

        static int j1(int b)

        {

            int a = ;

            for (int i = ; i <= b; i++)

            {

                a = i * a;

            }

            return a;

        }

        /// <summary>

        /// 函数的递归求阶乘

        /// </summary>

        /// <param name="a"></param>

        /// <returns></returns>

        static int j(int a)

        {

            int b;

            if (a <= )

            {

                return ;//初始值

            }

            else

            {

                b = a * j(a - );//递推关系

            }

            return b;

        }

    }

}