stdlib
int semaphore type
semaphore signal semaphore as semaphore sub as int $1 1
semaphore wait semaphore as semaphore add as int $1 1

void dosemaphores int as int wait signal wait wait as semaphore 0

int int coord type
int int swap int int $2 $1
int int mkcoord coord as coord $1 $2
coord getxy int int as int int $1

int int main int int int
  getxy mkcoord $1 $2
  dosemaphores