#include <iostream>
using namespace std;

void swap(int &x, int &y)      //passing the reference
{
  int temp;
  temp = x;
  x=y;
  y = temp;
}

int main()
{
  int a, b;
  a=10;
  b=20;
  swap(a,b);
  
  cout << "a = "<<a <<", b = "<<b << endl;     //a = 10, b = 20
  
  return 0;
}