f
a
f
b
f
a
x
f
a
f
b
f
b
f
a
x
f
b
f
b
f
b
x
f
b
f
b
x
2.2
f
a
f
b
f
a
x
f
b
f
b
f
a
x
f
a
f
b
f
a
x
f
a
f
b
f
b
f
a
x
true
f
a
f
b
f
a
x
f
a
f
b
f
b
f
a
x
true
2
1
a
0
1
2
b
0
1
1
f
2
0
0
0
1
1
0
0
1
0
2
8946
0
f
2
1
1
1
1
2
0
0
f
a
f
b
f
a
x
f
a
f
b
f
b
f
a
x
f
b
f
b
f
b
x
f
b
f
b
x
f
a
f
b
f
a
x
f
b
f
b
f
a
x
false
NaTT
certifiable-1.6