1
1
1
3
4
7
8
8
9
9
9
B
C
C
D
D
D
D
E
E
E
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F