Find Greatest and Smallest Number

Design

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 _6th_Program_Smallest_Greatest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {  
            
            int a, b, c;

            a = Convert.ToInt16(textBox1.Text);
            b = Convert.ToInt16(textBox2.Text);
            c = Convert.ToInt16(textBox3.Text);

            if (a > b && a > c)
            {
                textBox4.Text = "First Number is Greatest";
            }
            else if (b > a && b > c)
            {
                textBox4.Text = "Second Number is Greatest";
            }
            else
            {
                textBox4.Text = "Third Number is Greatest";
            }
            
        }
    } 
} 

Output