a
a
b
b
x1
b
b
c
c
a
a
x1
b
b
c
c
x1
c
c
b
b
b
b
x1
a
a
c
c
x1
c
c
a
a
b
b
x1
2.2
b
b
c
c
x1
b
b
b
x1
a
a
c
c
x1
a
b
b
x1
a
a
b
b
x1
b
b
c
c
a
a
x1
a
a
b
b
x1
a
a
x1
a
a
b
b
x1
a
x1
a
a
c
c
x1
b
b
x1
a
a
b
b
x1
b
c
c
a
a
x1
a
a
c
c
x1
a
a
b
b
x1
b
b
c
c
x1
b
b
x1
b
b
c
c
x1
b
b
b
b
x1
a
a
c
c
x1
b
x1
b
b
c
c
x1
b
x1
true
a
a
b
b
x1
a
x1
a
a
b
b
x1
a
a
x1
a
a
c
c
x1
a
b
b
x1
a
a
c
c
x1
a
a
b
b
x1
true
a
1
1
7758
b
1
1
0
c
1
1
0
a
1
1
0
b
1
0
a
a
c
c
x1
a
a
b
b
x1
a
a
b
b
x1
a
a
x1
a
a
b
b
x1
b
b
c
c
a
a
x1
a
a
c
c
x1
c
c
a
a
b
b
x1
b
b
c
c
x1
c
c
b
b
b
b
x1
a
a
b
b
x1
a
a
x1
a
a
c
c
x1
a
a
b
b
x1
true
Failed!
NaTT
certifiable-1.6