#include <iostream>
using namespace std;

void swap(int &x, int &y)
{
 int temp;
 temp = x;
 x = y;
 y = temp;
 return;
}

int main()
{
 int a = 100, b = 200;
 cout << a << b << endl;

 swap(a, b);
 cout << a << b << endl;

 return 0;
}