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