#include <iostream>

using namespace std;

​

void swapNums(int &x, int &y) {

  int z = x;

  x = y;

  y = z;

}

​

int main() {

  int firstNum = 10;

  int secondNum = 20;

​

  cout << "Before swap: " << "\n";

  cout << firstNum << secondNum << "\n";

​

  swapNums(firstNum, secondNum);

​

  cout << "After swap: " << "\n";

  cout << firstNum << secondNum << "\n";

​

  return 0;

}

​