C# da Try Catch ile İşlem Yapma

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            int s1, s2;
            double ort;
            try
            {
                s1 = Convert.ToInt32(textBox1.Text);
                s2 = Convert.ToInt32(textBox2.Text);
                if ((s1<0 || s1>100)||(s2<0||s2>100))
                {
                    throw new Exception();
                }
                ort = (s1 + s2) / 2.0;
                label4.Text = ort.ToString();
            }
            catch (Exception)
            {

                MessageBox.Show("0-100  arası tam sayı giriniz ");
            }
        }
    }
}