a__f
b
X
c
a__f
X
a__c
X
a__c
b
mark
f
X1
X2
X3
a__f
X1
mark
X2
X3
mark
c
a__c
mark
b
b
a__f
X1
X2
X3
f
X1
X2
X3
a__c
c
2.2
mark
f
X1
X2
X3
mark
X2
mark
c
a__c
a__f
b
X
c
a__f
X
a__c
X
mark
f
X1
X2
X3
a__f
X1
mark
X2
X3
a__f
b
X
c
a__c
true
mark
f
X1
X2
X3
mark
X2
true
a__c
0
0
b
0
0
a__f
3
0
c
0
0
f
3
2
1
mark
1
1
0
mark
1
0
a__f
3
0
a__c
0
0
mark
f
X1
X2
X3
a__f
X1
mark
X2
X3
false
a__f
b
X
c
a__f
X
a__c
X
true
Failed!
NaTT
certifiable-1.6