18               3             10  13  17
  10               3             5   8   9
  13               2             11  12
  17               3             14  15  16
  5                2             1  4
  8                2             6  7
  9                0
  11               0
  12               0
  14               0
  15               0
  16               0
  1                0
  4                2              2  3
  6                0
  7                0
  2                0
  3                0