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