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