TWO NUMBERS INTERCHANGE WITHOUT USING THE THIRD VARIABLE IN C++

#include<iostream.h>

#include<conio.h>

void main()

{

  clrscr();

  int a,b;

  cout<<"enter  the value of number 1 =”;

  cin>>a;

  cout<<"enter  the value of number 2";

  cin>>b;

  a=a+b;

  b=a-b;

  a=a-b;

  /*THIS PROGRAM ACCEPT TWO NUMBERS AS INPUT AND GENERATE TWO NUMBER IN OUTPUT BY     SWAPPING THEIR VALUES*/

  cout<<"\n"<<"after interchanging value of"<<" number 1 ="<<a<<"\n"<<" number  2="<<b;

  getch();

}