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