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