Swap two variables without using third variable. C/ C++

Problem#2

#include <iostream.h>
int main(){

  int x=1,y=2;
  cout<<"x :=:"<<x<<"\ny :=:"<<y<<"\n";
  x+=y; 
  y=x-y;
  x-=y;
  cout<<"\nx :=:"<<x<<"\ny :=:"<<y<<"\n";
  return 0;
}