x 0
x
8 0
7 x x
6 0
5 0
c c
b b
d
c
b
a
x q q q q 4 3 2 1
4
8 8
4 4
4
3
7 7
3 3
3
2
6 6
2 2
2
1
5 5
1 1
1
a a
a
b b
b
c c
c
d d
d
0 0 x x 8 7 6 5
0 0 0 0 x 0 x 0
x