-er bbb bbc bbe bbg bbk bbn bbr bcb bcc bce bcg bck bcn bcr be- beb bec bee beg bek ben ber bgb bgc bge bgg bgk bgn bgr bkb bkc bke bkg bkk bkn bkr bnb bnc bne bng bnk bnn bnr brb bre brg brk brn brr c-- cbb cbc cbe cbg cbk cbn cbr ccb ccc cce ccg cck ccn ccr ce- ceb cec cee ceg cek cen cer cgb cgc cge cgg cgn cgr ckb ckc cn- cnb cnc cne cng cnn cnr crb crc cre crg crk crn crr ebb ebc ebe ebg ebk ebn ebr ec- ecb ecc ece ecg eck ecn ecr eeb eec eee eeg eek een eer egb egc ege egg egn egr ekb ekc eke ekg ekr en- enb enc ene eng enk enn enr erb erc ere erg erk ern err gbc gbe gbg gbk gbn gbr gcb gcc gce gcg gck gcn gcr ge- geb gec gee geg gek gen ger ggb ggc ggg ggn ggr gkb gkn gnb gnc gne gnn gnr grb grc gre grg grk grn grr kbb kbc kbe kbk kbn kbr kcb kcc kce kcg kck kcn kcr ke- keb kec kee keg kek ken ker kgb kgc kkb kkc kke kkk kkn kkr kn- knc kne kng knk knn knr krc krg krk krn krr nbb nbc nbe nbg nbk nbn nbr ncb ncc nce ncg nck ncn ncr ne- neb nec nee neg nek nen ner ngb ngc nge ngg ngk ngn nkc nke nkk nkn nkr nnb nnc nne nng nnk nnn nrb nrc nre nrg nrk nrn nrr rbb rbc rbe rbg rbk rbn rbr rcb rcc rce rcg rcn rcr re- reb rec ree reg rek ren rer rgb rgc rge rgg rgk rgn rgr rkb rkc rke rkg rkk rnb rnc rng rnn rnr rrb rrc rrg rrk rrn rrr