The zone for (10, 4) is bounded by walls
    0
    3
    5
The zone for (0, 6) is bounded by walls
    0
    2
    3
    5
    6
The zone for (8, 20) is bounded by walls
    0
    1
    2
    5
    6
The zone for (26, 6) is bounded by walls
    1
    2
    4