Ww ------+--------+--------+--------+-------- Ww W | WW Ww w | wW ww | ww ww w | wW ww | ww | W W | WW Ww | Ww WW | Ww WW | Ww WW | WW Ww | wW | ww wW | ww wW | ww wW | ww ww w