-er b-u bbb bbc bbe bbk bbn bbr bbu bcb bcc bce bck bcn bcr bcu be- beb bec bee bek ben ber beu bkb bkc bke bkk bkn bkr bnb bnc bne bnk bnn bnr bnu brb bre brk brn brr bru bub buc bue buk bun bur buu c-- cbb cbc cbe cbk cbn cbr cbu ccb ccc cce cck ccn ccr ccu ce- ceb cec cee cek cen cer ceu ckb ckc cn- cnb cnc cne cnn cnr cnu crb crc cre crk crn crr cru cub cuc cue cuk cun cur cuu ebb ebc ebe ebk ebn ebr ebu ec- ecb ecc ece eck ecn ecr ecu eeb eec eee eek een eer ekb ekc eke ekr eku en- enb enc ene enk enn enr enu erb erc ere erk ern err eru eu- eub euc eue eun eur kbb kbc kbe kbk kbn kbr kbu kcb kcc kce kck kcn kcr kcu ke- keb kec kee kek ken ker kkb kkc kke kkk kkn kkr kku kn- knc kne knk knn knr knu krc krk krn krr kru kub kuc kue kuk kun kur kuu nbb nbc nbe nbk nbn nbr nbu ncb ncc nce nck ncn ncr ncu ne- neb nec nee nek nen ner neu nkc nke nkk nkn nkr nku nnb nnc nne nnk nnn nnu nrb nrc nre nrk nrn nrr nru nub nuc nue nuk nun nur nuu rbb rbc rbe rbk rbn rbr rbu rcb rcc rce rcn rcr rcu re- reb rec ree rek ren rer reu rkb rkc rke rkk rku rnb rnc rnn rnr rnu rrb rrc rrk rrn rrr rru rub ruc rue ruk run rur ruu ubb ubc ube ubk ubn ubr ubu ucb ucc uce uck ucn ucr ucu ueb uec uee uen uer ukb ukc uke ukk ukn ukr uku un- unb unc une unk unn unr unu ur- urb urc ure urk urn urr uru uuc uue uun uur uuu