C++ code to swap two variables without using third variable

#include<iostream>


int main()

{

int var1, var2;

 cout<<"Enter value for first integer:  ";

 cin>>var1;

 cout<<"Enter value for second integer:  ";

 cin>>var2;

 cout<<" Values Before swapping:  "<<endl;

 cout<<"First Integer ="<<var1<<endl;

 cout<<"Second Interger ="<<var2<<endl;

              var1=var1+var2;

              var2=var1-var2;

              var1=var1-var2;

 cout<<" Values After swapping:  "<<endl;

 cout<<"First Integer ="<<var1<<endl;

 cout<<"Second Interger ="<<var2<<endl;

    return 0;

}