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