-er bbb bbc bbe bbf bbg bbk bbo bbr bcb bcc bce bcf bcg bck bco bcr be- beb bec bee bef beg bek beo ber bfb bfc bfe bff bfg bfo bfr bgb bgc bge bgf bgg bgk bgo bgr bkb bkc bke bkf bkg bkk bko bkr bob boc boe bof bog bok boo bor brb bre brf brg brk bro brr c-- cbb cbc cbe cbf cbg cbk cbo cbr ccb ccc cce ccf ccg cck cco ccr ce- ceb cec cee cef ceg cek ceo cer cfb cfc cfe cff cfg cfk cfo cfr cgb cgc cge cgg cgo cgr ckb ckc cko co- cob coc coe cof cog cok coo cor crb crc cre crf crg crk cro crr ebb ebc ebe ebf ebg ebk ebo ebr ec- ecb ecc ece ecf ecg eck eco ecr eeb eec eee eef eeg eek eeo eer ef- efb efc efe eff efg efo efr egb egc ege egf egg ego egr ekb ekc eke ekf ekg eko ekr eo- eob eoc eoe eof eog eok eoo eor erb erc ere erf erg erk ero err fbb fbc fbe fbf fbg fbk fbo fbr fcb fcc fce fcf fcg fck fco fcr feb fec fee fef feg fek feo fer ffc ffe fff ffg ffk ffo ffr fgb fgc fge fgf fgg fgr fkb fkc fkf fkg fkk fob foc foe fof fog fok foo for frb frc fre frf frg frk fro frr gbc gbe gbf gbg gbk gbo gbr gcb gcc gce gcf gcg gck gco gcr ge- geb gec gee gef geg gek geo ger gfb gfc gfe gff gfk gfo gfr ggb ggc ggg ggo ggr gkb gko gob goc goe gof gog gok goo gor grb grc gre grf grg grk gro grr kbb kbc kbe kbf kbk kbo kbr kcb kcc kce kcg kck kcr ke- keb kec kee kef keg kek keo ker kfc kff kfg kfo kgb kgc kgf kgo kkb kkc kke kkk kkr kob koc koe kof kog kok koo kor krc krf krg krk kro krr ob- obb obc obe obf obg obk obo obr oc- ocb occ ocf ocg ock oco ocr oeb oec oee oef oeg oeo oer of- ofb ofc ofe off ofg ofo ofr ogc oge ogf ogg ogo okb okc oke okg okk oko okr oo- oob ooc oof oog ook ooo oor or- orb orc ore orf org ork oro orr rbb rbc rbe rbf rbg rbk rbo rbr rcb rcc rce rcf rcg rco rcr re- reb rec ree ref reg rek reo rer rfb rfc rfe rff rfg rfk rfo rfr rgb rgc rge rgf rgg rgk rgo rgr rkb rkc rke rkf rkg rkk rko rob roc roe rof rog rok roo ror rrb rrc rrf rrg rrk rrr