a c a d b c b d c e d e k e l e s c t k s c t l s e t e g x x h x x f x pair x y s x t y a 0 c 0 d 0 b 0 e 0 k 0 l 0 s 1 t 1 g 2 h 2 f 1 pair 2 ORIENTED FULL