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