a
x1
b
x1
b
b
x1
c
x1
c
a
c
x1
a
b
c
a
x1
2.2
c
a
c
x1
a
b
c
a
x1
a
x1
b
x1
c
a
c
x1
a
x1
c
a
c
x1
b
c
a
x1
b
b
x1
c
x1
c
a
c
x1
c
a
x1
true
c
a
c
x1
c
a
x1
b
b
x1
c
x1
c
a
c
x1
b
c
a
x1
a
x1
b
x1
c
a
c
x1
a
x1
c
a
c
x1
a
b
c
a
x1
true
a
1
1
1
b
1
1
1
c
1
1
2
c
1
1
1
a
1
1
0
b
1
1
0
c
a
c
x1
a
b
c
a
x1
a
x1
b
x1
b
b
x1
c
x1
a
x1
b
x1
c
a
c
x1
a
b
c
a
x1
b
b
x1
c
x1
a
x1
b
x1
c
a
c
x1
a
b
c
a
x1
b
b
x1
c
x1
true
Failed!
NaTT
certifiable-1.6