9
1 -> (2,4) -> (8,8)
2 -> (1,4) -> (3,8) -> (8,11)
3 -> (2,8) -> (4,7) -> (6,4) -> (9,2)
4 -> (3,7) -> (5,9) -> (6,14)
5 -> (4,9) -> (6,10)
6 -> (3,4) -> (4,14) -> (5,10) -> (7,2)
7 -> (6,2) -> (8,1) -> (9,6)
8 -> (1,8) -> (2,11) -> (7,1) -> (9,7)
9 -> (3,2) -> (7,6) -> (8,7)