........................
a
a
a
a
a
a
a
a
a
a
a
b
b
b
b
b
b
b
b
b
b
b
b
c
c
cc
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
d
d
d
d
d
d
d
d
d
