#include <iostream>
  
void swap(int *x, int *y);

int main()
{
    int x = 5, y = 10;
  
    std::cout << "Main. Before swap, x: " << x 
              << " y: " << y << "\n";
    swap(&x, &y);
    std::cout << "Main. After swap, x: " << x 
              << " y: " << y << "\n";
    return 0;
}
  
void swap(int *px, int *py)
{
    int temp;
  
    std::cout << "Swap. Before swap, *px: " << *px 
              << " *py: " << *py << "\n";
  
    temp = *px;
    *px = *py;
    *py = temp;
  
    std::cout << "Swap. After swap, *px: " << *px 
              << " *py: " << *py << "\n";
}