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