c#初学

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace ConsoleApplication2{    class Program    {        static void Main(string[] args)        {            try            {                stu stu1 = new stu();                Console.WriteLine("hello word");                int s1, s2, z = 0;                s1 = int.Parse(Console.ReadLine());                s2 = int.Parse(Console.ReadLine());                z = stu1.add(s1, s2);                Console.WriteLine(z);            }            catch (IndexOutOfRangeException e)            {                Console.WriteLine("hello word");             }                           }        public class stu        {            public int add(int x, int y)            {                return x + y;            }        }    }}