/*
   Lab : Lab2 
   Day : Tuesday  [ 05 Aug 08 ]

   Problem Number: 02
   Problem Title : Swapping without temporary variable
   
   Theory : 
     	What swapping means ?

      		swapping means excnange of values between two variable
                for example if two integer variable a and b have following values
                    a = 20     and     b = 10
                then after swapping values of a and b becoms as
                    a = 10     and     b = 20
  
        How to do it ?
		  
		well it's simple if we are allowed to use third variable
		let third variable is t, then following three setps will do the swapping
               
              	step 1:	t = a
		step 2: a = b
		step 3: b = t

		Our original problem do not allow us to use third variable
           	please note that in above solution value of a and b are changed in step 2 and 3.
               	in step 2, on assignment of value b to a the original value of a is lost and a gets new value equal to b
		
		it is a crutial step we have to preserve some information so that the value of a can be generated at later time when assigning any value to a in step 2

        	Please think in this direction.
		There can be many ways to preserve this information.
  		
		One of my suggestion is to assign sum of a and b, to a

              	step 1:	a = a + b
		step 2: b = a - b
		step 3: a = a - b

	Note : Try to re-write the code by using difference  			
*/

class sol_lab2_prob02{

   	public static void main(String args[])
	{
		int a, b;

		a = 10;		
		b = 20;

		System.out.println("Values before swapping");
		System.out.println(" a = "+ a +", b = "+ b);

                //main swapping steps
                a = a + b;
 		b = a - b;
		a = a - b;

		System.out.println("Values after swapping");
		System.out.println(" a = "+ a +", b = "+ b);
	}	
}