1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

2

4

6

6

8

9

9

9

A

A

B

B

B

C

E

E

E

E

E

E

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F