#include <stdio.h>
void swap(int *px, int *py) {
  int temp;

  temp = *py;
  *px = *py;
  *px = temp;
}

int main() {
  int x,y;
  x = 10;
  y = 20;
  printf("x=%d, y=%d", x, y);
  swap(&x, &y);
  printf("After swap:");
  printf("x=%d, y=%d", x, y);
}