40320,5040,720,120,24,6,2,1
-----------------------------
[5, 3]
[6, 4, 2]
[1, 2, 3, 5, 6, 7]
[[1, 3, 5, 7], [1, 2, 5, 6]]
------------------------------
{1, 2, 3, 5, 6, 7, 8, 9}
{1}
{2, 3, 6, 8, 9}
------------------------------
[[1 1 1 1 1]
 [1 0 0 0 1]
 [1 0 2 0 1]
 [1 0 0 0 1]
 [1 1 1 1 1]]
[(0, 1), (0, 3), (1, 0), (1, 4), (3, 0), (3, 4), (4, 1), (4, 3)]
------------------------------
1
6
[('D', 'E'), ('A', 'D'), ('B', 'E'), ('A', 'E'), ('B', 'F'), ('C', 'E')]
[[0 0 0 1 1 0 0]
 [0 0 0 0 1 1 0]
 [0 0 0 0 1 0 0]
 [1 0 0 0 1 0 0]
 [1 1 1 1 0 0 0]
 [0 1 0 0 0 0 0]
 [0 0 0 0 0 0 0]]
------------------------------
kiwi
apple
orange