a
b
x1
b
c
a
x1
b
c
x1
c
b
b
x1
a
c
x1
c
a
b
x1
a
a
x1
a
d
d
d
x1
d
a
x1
d
d
c
x1
a
d
d
c
x1
a
a
a
d
x1
e
e
f
f
x1
f
f
f
e
e
x1
e
x1
a
x1
b
d
x1
d
d
x1
2.2
b
c
x1
b
x1
a
d
d
c
x1
d
x1
a
c
x1
b
x1
e
e
f
f
x1
e
x1
d
a
x1
d
c
x1
a
c
x1
a
b
x1
a
b
x1
b
c
a
x1
a
a
x1
d
x1
b
d
x1
d
d
x1
d
a
x1
d
d
c
x1
a
d
d
c
x1
a
d
x1
a
a
x1
a
d
d
d
x1
a
a
x1
d
d
x1
e
x1
a
x1
a
d
d
c
x1
a
a
a
d
x1
b
c
x1
b
b
x1
e
e
f
f
x1
e
e
x1
a
b
x1
a
x1
a
d
d
c
x1
a
a
d
x1
a
a
x1
d
d
d
x1
true
e
e
f
f
x1
e
e
x1
e
e
f
f
x1
e
x1
true
a
1
1
d
1
1
b
1
1
e
1
1
0
c
1
1
f
1
1
0
d
1
0
e
1
1
1
a
1
0
b
1
0
e
e
f
f
x1
e
e
x1
a
a
x1
a
d
d
d
x1
e
x1
a
x1
a
b
x1
b
c
a
x1
a
c
x1
c
a
b
x1
d
a
x1
d
d
c
x1
e
e
f
f
x1
f
f
f
e
e
x1
b
d
x1
d
d
x1
a
d
d
c
x1
a
a
a
d
x1
b
c
x1
c
b
b
x1
e
e
f
f
x1
e
e
x1
true
d
1
1
b
1
1
e
1
1
a
1
0
c
1
0
f
1
0
1
d
1
0
e
1
1
1
a
1
0
b
1
0
a
1
0
c
1
0
f
1
1
0
d
1
0
e
1
1
0
a
1
0
b
1
0
a
a
x1
a
d
d
d
x1
e
x1
a
x1
a
b
x1
b
c
a
x1
a
c
x1
c
a
b
x1
d
a
x1
d
d
c
x1
e
e
f
f
x1
f
f
f
e
e
x1
b
d
x1
d
d
x1
a
d
d
c
x1
a
a
a
d
x1
b
c
x1
c
b
b
x1
e
x1
a
x1
false
a
d
d
c
x1
a
a
d
x1
a
b
x1
a
x1
a
c
x1
a
b
x1
a
d
d
c
x1
a
a
a
d
x1
a
a
x1
a
d
d
d
x1
a
d
d
c
x1
a
d
x1
true
Failed!
NaTT
certifiable-1.6