a
x1
b
x1
a
b
x1
c
a
c
a
x1
c
b
c
x1
b
x1
2.2
a
b
x1
a
c
a
x1
a
b
x1
c
a
x1
a
b
x1
c
a
c
a
x1
a
b
x1
a
x1
true
a
b
x1
a
x1
a
b
x1
a
c
a
x1
true
a
1
1
2438
b
1
1
2438
c
1
1
0
c
1
0
a
1
1
0
a
b
x1
a
c
a
x1
a
x1
b
x1
c
b
c
x1
b
x1
a
b
x1
c
a
c
a
x1
a
b
x1
a
c
a
x1
true
Failed!
NaTT
certifiable-1.6