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