extern line();

void gbox(x1, y1, x2, y2)
int x1, y1, x2, y2;
{
  line(x1, y1, x2, y1);
  line(x1, y1, x1, y2);
  line(x2, y1, x2, y2);
  line(x2, y2, x1, y2);
}