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