0 1 2 2 3 4 5 5 6 7 0 [] 0 1 [0] 0 2 [0,1] 0 2 [0,1] 1 3 [] 0 4 [0] 0 5 [0,1] 0 5 [0,1] 1 6 [] 0 7 [0] 0 8 [0,1] 0 8 [0,1] 1 9 [] 0