C# Program to Swap two numbers without using third variable

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SwapNumbers
{
 class Program
 {
 static void Main(string[] args)
 {

int iFirstNumber, iSecondNumber;
 Console.WriteLine("C# Program to Swap two numbers without using third variable");
 Console.WriteLine("Enter the First Number");
 iFirstNumber = Convert.ToInt32(Console.ReadLine());
 Console.WriteLine("Enter the Second Number");
 iSecondNumber = Convert.ToInt32(Console.ReadLine());
 Console.WriteLine("Number before swapping");
 Console.WriteLine("First Number = {0}", iFirstNumber);
 Console.WriteLine("Second Number = {0}", iSecondNumber);
 
 iFirstNumber = iFirstNumber+iSecondNumber;
 iSecondNumber = iFirstNumber-iSecondNumber;
 iFirstNumber = iFirstNumber -iSecondNumber;
 Console.WriteLine("Number after swapping");
 Console.WriteLine("First Number = {0}", iFirstNumber);
 Console.WriteLine("Second Number = {0}", iSecondNumber);
 Console.ReadKey();

 }
 }
}