a b a a a b x1 c c a x1 c x1 b a a a b x1 2.2 c x1 a a b x1 a b a a a b x1 a x1 a b a a a b x1 c a x1 c x1 a b x1 c x1 a a a b x1 a b a a a b x1 c c a x1 true a b a a a b x1 c c a x1 c x1 a a a b x1 c x1 a b x1 a b a a a b x1 a x1 a b a a a b x1 c a x1 c x1 a a b x1 true Failed! NaTT certifiable-1.6