a
b
x1
b
d
x1
a
c
x1
d
d
d
x1
b
d
x1
a
c
b
x1
c
f
x1
d
d
c
x1
d
d
x1
f
x1
f
f
x1
a
x1
2.2
a
c
x1
d
d
x1
b
d
x1
a
c
b
x1
c
f
x1
c
x1
a
b
x1
b
d
x1
c
f
x1
d
d
c
x1
c
f
x1
d
c
x1
b
d
x1
c
b
x1
a
b
x1
d
x1
d
d
x1
f
x1
a
c
x1
d
x1
a
c
x1
d
d
d
x1
b
d
x1
b
x1
f
f
x1
a
x1
true
f
f
x1
a
x1
c
f
x1
d
c
x1
b
d
x1
b
x1
a
c
x1
d
d
d
x1
a
c
x1
d
x1
c
f
x1
d
d
c
x1
a
b
x1
b
d
x1
c
f
x1
c
x1
b
d
x1
a
c
b
x1
d
d
x1
f
x1
a
b
x1
d
x1
b
d
x1
c
b
x1
a
c
x1
d
d
x1
true
a
1
1
0
d
1
1
0
b
1
1
20538
c
1
1
0
f
1
1
0
d
1
1
0
f
1
1
0
c
1
1
0
a
1
1
0
b
1
1
20538
a
c
x1
d
d
x1
b
d
x1
c
b
x1
d
d
x1
f
x1
b
d
x1
a
c
b
x1
c
f
x1
c
x1
a
b
x1
b
d
x1
c
f
x1
d
d
c
x1
a
c
x1
d
x1
a
c
x1
d
d
d
x1
b
d
x1
b
x1
c
f
x1
d
c
x1
f
f
x1
a
x1
c
f
x1
d
d
c
x1
a
b
x1
b
d
x1
b
d
x1
a
c
b
x1
d
d
x1
f
x1
f
f
x1
a
x1
a
c
x1
d
d
d
x1
c
f
x1
c
x1
c
f
x1
d
c
x1
c
f
x1
d
d
c
x1
a
b
x1
b
d
x1
b
d
x1
b
x1
b
d
x1
c
b
x1
b
d
x1
a
c
b
x1
d
d
x1
f
x1
f
f
x1
a
x1
a
c
x1
d
x1
a
c
x1
d
d
x1
a
c
x1
d
d
d
x1
true
Failed!
NaTT
certifiable-1.6