#include <iostream>
using namespace std;

int main()
{
  int a = 4, b = 5;
  cout << "Before assignment: a: " << a << ", b: " << b << endl;
  pair<int&, int&> ba(b, a);
  ba = make_pair(a, b); // <===: (b, a) = (a, b)
  cout << "After assignment : a: " << a << ", b: " << b << endl;
  return 0;
}