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