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;
}
}
}
}