using System;

public class Program

{

    public static void Main()

    {

        int a = 4;

        int b = 12;

        Display(a,b);

        Swap(ref a, ref b);

        Display(a,b);

        //No coding here

    }

    //swap a's value with and b's value.

    private static void Swap(ref int a, ref int b){  //Ref means it'll be passed back

​

        /* Only code here */

        a+=b; //4+12=16

        b=a-b; //4-16=-12

        /*got this far on my own but then it stopped making sense*/

        a=a-b; //4--12=-8???

    }

    private static void Display(int a, int b){

        Console.WriteLine("A = {0}, B = {1}", a, b);

    }

}