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