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