void draw_line(SDL_Surface * s, int x0, int y0, int x1, int y1, unsigned color){
    unsigned x, y, count = x0;

    if(x0 != x1 && y1 != y0 && x0 < x1 && y0 < y1)
        for(y = y0; y < y1; y++){
            for(x = count; x < count+1; x++)
                put_pixel(s, x, y, RGB(color, color, color));
            count++;
        }
    else if(x0 != x1 && y1 != y0 && x0 > x1 && y0 < y1)
        for(y = y0; y < y1; y++){
            for(x = x1; x > count-1; x--)
                put_pixel(s, x, y, RGB(color, color, color));
            count--;
        }
    else if(x0 != x1 && y1 != y0 && x0 < x1 && y0 > y1)
        for(y = y1; y < y0; y--){
            for(x = count; x < count+1; x++)
                put_pixel(s, x, y, RGB(color, color, color));
            count++;
        }
    else if(x0 != x1 && y1 != y0 && x0 > x1 && y0 > y1)
        for(y = y1; y < y0; y--){
            for(x = x1; x > count-1; x--)
                put_pixel(s, x, y, RGB(color, color, color));
            count--;
        }
    else if(x0 != x1 && x0 < x1)
        for(x = x0; x < x1; x++)
            put_pixel(s, x, y, RGB(color, color, color));
    else if(x0 != x1 && x0 > x1)
        for(x = x1; x > x0; x--)
            put_pixel(s, x, y, RGB(color, color, color));
    else if(y0 != y1 && y0 < y1)
        for(y = y0; y < y1; y++)
            put_pixel(s, x, y, RGB(color, color, color));
    else if(y0 != y1 && y0 < y1)
        for(y = y1; y > y0; y--)
            put_pixel(s, x, y, RGB(color, color, color));
}