template <typename Z> inline Z sgn(Z x)
{
    return (x < 0? -1 : (x > 0? 1 : 0));
}

            int dx = targ->x - monster->x;
            if (dx) 
                dx /= dx;

            int dx = sgn(targ->x - monster->x);
            int dy = sgn(targ->y - monster->y);

            int dy = targ->y - monster->y;
            if (dy) 
                dy /= dy;

    // No multiple ghosts until level 14 of the Main Dungeon.

    // No multiple ghosts until level 9 of the Main Dungeon.