Swap Two Variables Without Using a Third Variable in C#

In most  swap operations, we use a third variable. The following code snippet shows how we can use just two int variables to swap their values.

using System;
namespace swap
{
    class Program
    {
        static void Main(string[] args)
        {
            int first, second;
            Console.WriteLine("ENTER THE FIRST NO");
            first = int.Parse(Console.ReadLine());
            Console.WriteLine("ENTER THE Second NO");
            second = int.Parse(Console.ReadLine());
            if (first != second)
            {
                first = first + second;
                second = first - second;
                first = first - second;
                Console.WriteLine("The First No is After Swapping   {0}", first);
                Console.WriteLine("The Second No is After Swapping {0}", second);
                Console.ReadLine();
            }
            else
                Console.WriteLine("The First and Second No Should be Different");
            Console.ReadLine();
        }
    }
}