-er b-u bbb bbc bbe bbg bbk bbn bbr bbu bcb bcc bce bcg bck bcn bcr bcu be- beb bec bee beg bek ben ber beu bgb bgc bge bgg bgk bgn bgr bgu bkb bkc bke bkg bkk bkn bkr bnb bnc bne bng bnk bnn bnr bnu brb bre brg brk brn brr bru bub buc bue bug buk bun bur buu c-- cbb cbc cbe cbg cbk cbn cbr cbu ccb ccc cce ccg cck ccn ccr ccu ce- ceb cec cee ceg cek cen cer ceu cgb cgc cge cgg cgn cgr cgu ckb ckc cn- cnb cnc cne cng cnn cnr cnu crb crc cre crg crk crn crr cru cub cuc cue cug cuk cun cur cuu ebb ebc ebe ebg ebk ebn ebr ebu ec- ecb ecc ece ecg eck ecn ecr ecu eeb eec eee eeg eek een eer egb egc ege egg egn egr egu ekb ekc eke ekg ekr eku en- enb enc ene eng enk enn enr enu erb erc ere erg erk ern err eru eu- eub euc eue eug eun eur gbc gbe gbg gbk gbn gbr gbu gcb gcc gce gcg gck gcn gcr gcu ge- geb gec gee geg gek gen ger geu ggb ggc ggg ggn ggr ggu gkb gkn gnb gnc gne gnn gnr gnu grb grc gre grg grk grn grr gru gu- gub guc gue gug guk gun gur guu kbb kbc kbe kbk kbn kbr kbu kcb kcc kce kcg kck kcn kcr kcu ke- keb kec kee keg kek ken ker kgb kgc kgu kkb kkc kke kkk kkn kkr kku kn- knc kne kng knk knn knr knu krc krg krk krn krr kru kub kuc kue kug kuk kun kur kuu nbb nbc nbe nbg nbk nbn nbr nbu ncb ncc nce ncg nck ncn ncr ncu ne- neb nec nee neg nek nen ner neu ngb ngc nge ngg ngk ngn ngu nkc nke nkk nkn nkr nku nnb nnc nne nng nnk nnn nnu nrb nrc nre nrg nrk nrn nrr nru nub nuc nue nug nuk nun nur nuu rbb rbc rbe rbg rbk rbn rbr rbu rcb rcc rce rcg rcn rcr rcu re- reb rec ree reg rek ren rer reu rgb rgc rge rgg rgk rgn rgr rkb rkc rke rkg rkk rku rnb rnc rng rnn rnr rnu rrb rrc rrg rrk rrn rrr rru rub ruc rue rug ruk run rur ruu ubb ubc ube ubg ubk ubn ubr ubu ucb ucc uce ucg uck ucn ucr ucu ueb uec uee ueg uen uer ugb ugc uge ugg ugk ugn ugr ugu ukb ukc uke ukk ukn ukr uku un- unb unc une ung unk unn unr unu ur- urb urc ure urg urk urn urr uru uuc uue uug uun uur uuu