40-39-41
                      |
                   37-36-38-42-43-44
                      |           |
                   34-33-35    49-45-50
                      |           |
                   31-30-32    51-46-52
                      |           |
                   27-26-29    53-47-54
                      |           |
                   25-24-28    55-48-56-57-out
                      |
                      23
                      |
       4  12 14 16 18 21  22
       |  |  |  |  |  |   |
    1--2--5--6--7--8--9--10
    |  |  |  |  |  |  |   |
    |  3  11 13 15 17 19  20
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