N
unstable
N
N
c
c
c
c
c
c
c
c
unstable
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
unstable
c
c
c
c
unstable
c
unstable
c
unstable
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
I
c
c
c
c
c
c
I
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
unstable
c
c
I
v
I
I
I
I
I
I
I
I
I
I
I
I
I
v
I
I
v
I
I
I
v
I
I
v
I
v
I
I
unstable
I
unstable
I
I
I
I
I
unstable
I
unstable
I
unstable
I
unstable
I
unstable
I
I
unstable
I
I
I
I
unstable
I
unstable
I
unstable
I
I
I
I
I
I
unstable
I
I
unstable
I
I
I
I
I
I
I
I
I
unstable
I
I
I
I
I
unstable
I
I
I
I
I
I
I
I
I
I
I
I
I
I
unstable
I
unstable
I
I
unstable
I
unstable
I
I
I
I
I
unstable
I
unstable
I
I
I
I
unstable
I
unstable
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
v
I
I
v
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
v
I
I
v
I
I
I
I
I
v
I
I
v
I
I
I
v
I
I
I
I
I
I
I
I
I
I
I
I
v
I
I
v
I
I
v
I
I
v
I
v
I
I
v
I
I
v
I
v
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
unstable
I
unstable
I
I
unstable
I
I
I
unstable
I
v
I
v
I
I
I
I
v
I
T
T
T
T
T
T
T
unstable
T
unstable
T
T
unstable
T
T
T
T
T
T
T
unstable
T
T
unstable
T
unstable
T
unstable
T
unstable
T
unstable
T
unstable
T
T
unstable
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
f
f
f
f
f
f
f
f
f
unstable
f
f
f
f
f
f
f
unstable
f
unstable
f
unstable
f
f
f
f
f
unstable
f
f
f
unstable
f
f
f
f
f
unstable
f
unstable
f
f
f
f
f
f
f
unstable
f
unstable
f
unstable
f
unstable
f
unstable
f
unstable
f
f
f
f
f
f
f
f
unstable
f
unstable
f
f
unstable
f
f
f
f
f
f
f
f
f
f
f
unstable
f
f
f
unstable
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
unstable
f
f
f
f
f
f
f
f
unstable
f
f
f
f
unstable
f
f
unstable
f
unstable
f
unstable
f
unstable
f
f
f
f
f
f
unstable
f
f
f
f
unstable
f
unstable
f
unstable
f
f
unstable
f
unstable
f
f
f
f
f
f
f
f
f
f
f
unstable
f
f
f
f
f
f
f
f
f
f
f
f
E
unstable
E