const int XMAX=40;
const int YMAX=24;
struct point {
   int x,y;
   point() {}
   point(int a, int b) { x=a; y=b; }
};
extern void put_point(int a, int b);
inline void put_point(point p) { put_point(p.x, p.y); }
extern void put_line(int, int, int, int);
inline void put_line(point a, point b)
    { put_line(a.x, a.y, b.x, b.y); }
extern void screen_init();
extern void screen_destroy();
extern void screen_refresh();
extern void screen_clear();