1 2

1 2

1 2

1 2

1 2 3 4

1 2 3 4 5

1 2

1 2

1 2 3 4 5

1 2 3 4 5 6 ...12

1 2 3 4 5 6 ...9

1 2 3 4 5 6

1 2 3

1 2 3 4 5 6 ...8

1 2