a
a
a
a
x1
b
b
b
b
b
b
x1
b
b
b
b
x1
c
c
c
c
c
c
x1
c
c
c
c
x1
d
d
d
d
d
d
x1
b
b
x1
d
d
d
d
x1
c
c
d
d
d
d
x1
a
a
x1
2.2
b
b
b
b
x1
c
c
c
c
c
x1
b
b
b
b
x1
c
x1
a
a
a
a
x1
b
b
x1
a
a
a
a
x1
b
b
b
b
b
b
x1
a
a
a
a
x1
b
b
b
b
x1
a
a
a
a
x1
b
b
b
x1
a
a
a
a
x1
b
x1
c
c
d
d
d
d
x1
a
a
x1
a
a
a
a
x1
b
b
b
b
b
x1
b
b
b
b
x1
c
c
x1
b
b
b
b
x1
c
c
c
c
x1
b
b
b
b
x1
c
c
c
c
c
c
x1
c
c
d
d
d
d
x1
a
x1
b
b
b
b
x1
c
c
c
x1
true
b
b
b
b
x1
c
c
c
x1
a
a
a
a
x1
b
x1
a
a
a
a
x1
b
b
b
x1
c
c
d
d
d
d
x1
a
x1
b
b
b
b
x1
c
c
c
c
c
c
x1
b
b
b
b
x1
c
c
c
c
x1
a
a
a
a
x1
b
b
b
b
x1
a
a
a
a
x1
b
b
b
b
b
b
x1
a
a
a
a
x1
b
b
x1
b
b
b
b
x1
c
x1
b
b
b
b
x1
c
c
x1
a
a
a
a
x1
b
b
b
b
b
x1
c
c
d
d
d
d
x1
a
a
x1
b
b
b
b
x1
c
c
c
c
c
x1
true
a
1
1
56
d
1
1
16
b
1
1
37
c
1
1
24
c
1
1
0
a
1
1
30
b
1
1
11
b
b
x1
d
d
d
d
x1
a
a
a
a
x1
b
b
b
b
b
b
x1
c
c
c
c
x1
d
d
d
d
d
d
x1
c
c
d
d
d
d
x1
a
a
x1
b
b
b
b
x1
c
c
c
c
c
c
x1
NaTT
certifiable-1.6