Write a Program to swap two numbers without using third variable.

#include<iostream>
using namespace std;
int main()
{
int num1,num2;
cout<<"Enter 1st number: ";
cin>>num1;
cout<<"Enter 2nd number: ";
cin>>num2;
num1=num1+num2;
num2=num1-num2;
num1=num1-num2;
cout<<"The 1st number is: "<<num1<<endl;
cout<<"The 2nd number is: "<<num2;
}