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