[[3, 9], [6, 8], [9, 10], [7, 8], [8, 10], [7, 10], [1, 9], [8, 9], [6, 9], [2, 7]]
[[1, 9, 3, 10, 8, 6, 7, 2], [4], [5]]
2
[[1, 4], [4, 5]]