void draw_line(int x1, int y1, int x2, int y2);
void draw_smooth(int x1, int y1, int x2, int y2, int x3, int y3);
void smooth_draw(int x1, int y1, int x2, int y2, int x3, int y3);
void draw_line(int x1, int y1, int x2, int y2);
void draw_smooth(int x1, int y1, int x2, int y2, int x3, int y3);
void smooth_draw(int x1, int y1, int x2, int y2, int x3, int y3);