b
b
b
a
b
b
b
b
b
b
a
a
d
d
b
b
d
b
b
d
g
e
d
a
f
d
a
g
b
c
b
e
e
f
a
f
b
d
c
d
b
a
b
c
d
e
f
g
c
d
b
d
d
b
b
b
c
b
d
f
b
b
d
b
c
c
b
a
a
a
a
d
d
d
c
a
b
b
b
a