[[1, 2, 3, 4]]
[[1, 2, 3, 4], [1, 2, 4]]
[[1, 2, 3, 4], [1, 2, 4], [1, 2, 5]]
[[1, 2, 3, 4], [1, 2, 4], [1, 2, 5], [1, 3, 4]]
[[1, 2, 3, 4], [1, 2, 4], [1, 2, 5], [1, 3, 4], [2, 3, 4]]
[[1, 2, 3, 4], [1, 2, 4], [1, 2, 5], [1, 3, 4], [2, 3, 4], [2, 4]]
[[1, 2, 3, 4], [1, 2, 4], [1, 2, 5], [1, 3, 4], [2, 3, 4], [2, 4], [2, 5]]
3