-er bbb bbe bbg bbk bbo bbr bbs be- beb bee beg bek beo ber bes bgb bge bgg bgk bgo bgr bgs bkb bke bkg bkk bko bkr bks bob boe bog bok boo bor bos brb bre brg brk bro brr brs bsb bse bsg bsk bso bsr bss ebb ebe ebg ebk ebo ebr ebs eeb eee eeg eek eeo eer ees egb ege egg ego egr egs ekb eke ekg eko ekr eks eo- eob eoe eog eok eoo eor eos erb ere erg erk ero err ers es- esb ese esg esk eso esr ess gbe gbg gbk gbo gbr gbs ge- geb gee geg gek geo ger ges ggb ggg ggo ggr ggs gkb gko gks gob goe gog gok goo gor gos grb gre grg grk gro grr grs gsb gse gsg gsk gso gsr gss kbb kbe kbk kbo kbr kbs ke- keb kee keg kek keo ker kes kgb kgo kgs kkb kke kkk kkr kks kob koe kog kok koo kor kos krg krk kro krr krs ksb kse ksg ksk kso ksr kss ob- obb obe obg obk obo obr obs oeb oee oeg oeo oer oes oge ogg ogo ogs okb oke okg okk oko okr oks oo- oob oog ook ooo oor oos or- orb ore org ork oro orr ors os- osb ose osg osk oso osr oss rbb rbe rbg rbk rbo rbr rbs re- reb ree reg rek reo rer res rgb rge rgg rgk rgo rgr rgs rkb rke rkg rkk rko rks rob roe rog rok roo ror ros rrb rrg rrk rrr rrs rsb rse rsg rsk rso rsr rss sbb sbe sbg sbk sbo sbr sbs se- seb see seg sek seo ser ses sgb sge sgg sgk sgo sgr sgs sk- skb ske skg skk sko skr sks sob soe sog sok soo sor sos sr- srb sre srg srk sro srr srs ss- ssb sse ssg ssk sso ssr sss