b
B
x
B
b
x
b
c
d
x
B
c
D
x
D
d
x
d
D
x
a
P
x
a
b
b
x
B
P
x
P
b
x
b
c
d
x
P
c
Q
x
Q
D
x
d
Q
x
Q
e
x
d
d
e
x
2.2
b
c
d
x
D
x
D
d
x
D
x
a
P
x
a
b
b
x
a
P
x
b
x
b
B
x
B
b
x
a
P
x
b
b
x
B
P
x
b
x
b
c
d
x
Q
x
b
c
d
x
B
c
D
x
b
B
x
b
x
Q
D
x
Q
x
true
a
P
x
a
b
b
x
true
Failed!
NaTT
certifiable-1.6