#include <iostream>
using namespace std;

void swap(int* a, int* b)
{
 int tmp = *b; *b = *a; *a = tmp;
}

int main(void)
{
 int x = 10, y = 20;
 cout << x << ',' << y << endl;
 swap(&x, &y);
 cout << x << ',' << y << endl;
 return 0;
}