a
a
x1
b
c
c
c
x1
b
c
x1
d
d
d
d
x1
a
x1
d
c
d
x1
b
b
x1
c
c
c
x1
c
c
x1
d
d
d
x1
c
d
d
x1
a
x1
2.2
a
x1
c
d
x1
a
a
x1
c
x1
b
b
x1
c
x1
b
b
x1
c
c
c
x1
a
a
x1
c
c
x1
a
a
x1
b
c
c
c
x1
c
d
d
x1
a
x1
b
b
x1
c
c
x1
a
a
x1
c
c
c
x1
true
a
a
x1
c
c
c
x1
b
b
x1
c
c
x1
c
d
d
x1
a
x1
a
a
x1
b
c
c
c
x1
b
b
x1
c
x1
a
a
x1
c
x1
a
a
x1
c
c
x1
b
b
x1
c
c
c
x1
a
x1
c
d
x1
true
a
1
1
287
d
1
1
82
b
1
1
205
c
1
1
123
c
1
1
0
a
1
1
163
b
1
1
80
b
b
x1
c
c
c
x1
a
a
x1
b
c
c
c
x1
a
x1
d
c
d
x1
c
c
x1
d
d
d
x1
c
d
d
x1
a
x1
b
c
x1
d
d
d
d
x1
NaTT
certifiable-1.6