-er b-u bbb bbe bbk bbn bbr bbu be- beb bee bek ben ber beu bkb bke bkk bkn bkr bnb bne bnk bnn bnr bnu brb bre brk brn brr bru bub bue buk bun bur buu ebb ebe ebk ebn ebr ebu eeb eee eek een eer ekb eke ekr eku en- enb ene enk enn enr enu erb ere erk ern err eru eu- eub eue eun eur kbb kbe kbk kbn kbr kbu ke- keb kee kek ken ker kkb kke kkk kkn kkr kku kn- kne knk knn knr knu krk krn krr kru kub kue kuk kun kur kuu nbb nbe nbk nbn nbr nbu ne- neb nee nek nen ner neu nke nkk nkn nkr nku nnb nne nnk nnn nnu nrb nre nrk nrn nrr nru nub nue nuk nun nur nuu rbb rbe rbk rbn rbr rbu re- reb ree rek ren rer reu rkb rke rkk rku rnb rnn rnr rnu rrb rrk rrn rrr rru rub rue ruk run rur ruu ubb ube ubk ubn ubr ubu ueb uee uen uer ukb uke ukk ukn ukr uku un- unb une unk unn unr unu ur- urb ure urk urn urr uru uue uun uur uuu