Level    NorthDir EastDir SouthDir WestDir
1    2 0 0 0
2    3 0 1 0
3    4 0 2 0
4    0 3 3 3
5    6 0 4 0
6    7 0 5 0
7    8 0 6 0
8    9 0 0 0
9    13 0 6 0
10    0 11 7 0
11    0 12 8 10
12    15 13 0 11
13    0 0 9 12
14    0 15 0 0
15    17 0 12 14
16    0 17 0 0
17    0 18 15 16
18    0 0 0 17