1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

4

6

7

9

9

A

B

B

B

C

D

E

E

E

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F