1 1
r
r a b c d e f g h
c r
c 1
p e 1
p 1
p
p 1
s 1
p
p e 1
q p s
q 1
q
q 1
e 1
g 1
q
a b c d e f g h
n c 1
n 1
s n
s 1
r