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