9
8
x 0 0 9 9 4 3 2 1
0 0 9 9 4 3 2 1
A a a
B b b
C c c
t C A
a B t
a a
b A B
b C
b b
B C
A B
A A
t 1 a
1 t
a t
1 a
t t
u 2 b
2 u
b u
2 b
v 2 t
2 v
t v
2 t
u v
t 3 A
3 t
A t
3 A
v 3 u
3 v
u v
3 u
t v
t t
4 4
4 t
D 4 4
C 3 3
B 2 2
A 1 1
c 4 C
c c
c 2
c c
u c A
c 1
t D 3
t t
t 2
t t
t A
c t
c c
b 4 B
B 3
c B
a 3 2
a D
a a
a 1
b b
A b
b 1
a A
a a
t 3 1
3 t
1 t
1 3
1 1
1 4
1 1
1 2
a 1
t D
t t
t 2
b t
b b
b u
8 c c
t b b
8 t
8 8
t a a
8 t
8 9
8 8
8
0 0 0 0 9 0 9 0
9