0 [1, 3, 2, 1]
1 [3, 1]
0 [1]
2 [1, 4]
1 [1]
2 [3, 3, 1]
0 [3, 1]
0 [1]
1 [4]
! 1 [0]
! 1 [1, 0]
3
2 2 1