a
a
x1
b
c
x1
b
b
x1
c
d
x1
c
c
x1
d
d
d
x1
d
c
x1
b
f
x1
d
d
d
x1
a
c
x1
f
f
x1
f
b
x1
2.2
b
b
x1
d
x1
d
d
d
x1
c
x1
d
c
x1
f
x1
c
c
x1
d
x1
a
a
x1
c
x1
d
c
x1
b
f
x1
c
c
x1
d
d
d
x1
a
a
x1
b
c
x1
d
d
d
x1
a
c
x1
f
f
x1
f
b
x1
b
b
x1
c
d
x1
c
c
x1
d
d
x1
f
f
x1
b
x1
true
f
f
x1
b
x1
d
c
x1
b
f
x1
c
c
x1
d
d
x1
b
b
x1
c
d
x1
f
f
x1
f
b
x1
a
a
x1
c
x1
c
c
x1
d
x1
d
c
x1
f
x1
d
d
d
x1
c
x1
d
d
d
x1
a
c
x1
a
a
x1
b
c
x1
c
c
x1
d
d
d
x1
b
b
x1
d
x1
true
a
1
1
40
d
1
1
28
b
1
1
36
c
1
1
44
f
1
1
36
d
1
1
0
f
1
1
43
c
1
1
13
a
1
1
11
b
1
1
6
f
f
x1
f
b
x1
d
c
x1
b
f
x1
a
a
x1
b
c
x1
c
c
x1
d
d
d
x1
d
d
d
x1
a
c
x1
f
f
x1
f
b
x1
b
b
x1
c
d
x1
f
f
x1
f
b
x1
true
a
1
1
d
1
1
b
1
1
c
1
1
f
1
2
d
1
1
0
f
1
1
43
c
1
1
13
a
1
1
11
b
1
1
6
d
c
x1
b
f
x1
a
a
x1
b
c
x1
c
c
x1
d
d
d
x1
d
d
d
x1
a
c
x1
f
f
x1
f
b
x1
b
b
x1
c
d
x1
NaTT
certifiable-1.6