f
0
x1
s
0
x1
d
0
x1
0
x1
d
s
x1
s
s
d
x1
f
s
x1
d
f
x1
2.2
f
s
x1
d
f
x1
f
s
x1
f
x1
d
s
x1
d
x1
true
f
s
x1
f
x1
true
d
1
0
s
1
1
1
f
1
0
0
1
0
d
1
0
f
1
1
0
f
s
x1
d
f
x1
false
d
s
x1
d
x1
true
d
1
0
s
1
1
1
f
1
0
0
1
0
d
1
1
0
f
1
0
NaTT
certifiable-1.6