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