f
n
t n f t
ns ns
ns
n n
s F s e s F s e s F s
s e
Lts
Lt e t
s
t t t t
t t t
s
F s f t te t e e t t
s s s
s s
F s s s
s
s s
tt t
f t e
t t
F s f t e e
s s s
F s s s s s
f t t t
s s s s
F s s s
s s
f t t t t t
A B C D
s As B Cs D
s s
s s s s
s s
A B C D
s i
CD
A B
s s s
Ls s t t
Ls t t t
at at
se e at at at
s a
L
s a a
s a a s as a s as a
s s s
s a a s as a s as a
s a a s a a
a s as a s as a s as a s as a
s a s a
s a a s as a s as a
X s
x t
s X s s sX s X s
s X s sX s X s s
s X s X s s
s X s sX s X s s
s X s s s X s sX s
s
X s s s s s s s
t t
x t e e
s X s s X s
s X s X s
X s s
s X s s s X s X s
s X s s X s X s
s X s s X s X s s
s s
X s s s
s s s s
s X s sX s X s s
s s s
X s s s s s s
s
s X s s sX s X s s
s s
X s s s s s s
x x t x x
s
s X s X s s
s
X s
s
x t t t t t
t
x x x x x e t
s
s s X s s