-er a-a a-b aaa aab aae aag aak aao aar aas ab- aba abb abe abg abk abo abr abs aea aeb aee aeg aek aeo aer aes ag- aga agb age agg agk ago agr ags aka akb ake akg akk ako akr aks aoa aob aoe aog aok aoo aor aos ar- ara arb are arg ark aro arr ars as- asa asb ase asg ask aso asr ass baa bab bae bag bak bao bar bas bba bbb bbe bbg bbk bbo bbr bbs be- bea beb bee beg bek beo ber bes bga bgb bge bgg bgk bgo bgr bgs bka bkb bke bkg bkk bko bkr bks boa bob boe bog bok boo bor bos bra brb bre brg brk bro brr brs bsa bsb bse bsg bsk bso bsr bss eaa eab eae eag eak eao ear eas eba ebb ebe ebg ebk ebo ebr ebs eea eeb eee eeg eek eeo eer ees ega egb ege egg ego egr egs eka ekb eke ekg eko ekr eks eo- eoa eob eoe eog eok eoo eor eos era erb ere erg erk ero err ers es- esa esb ese esg esk eso esr ess gaa gab gae gag gak gao gar gas gba gbe gbg gbk gbo gbr gbs ge- gea geb gee geg gek geo ger ges gga ggb ggg ggo ggr ggs gka gkb gko gks goa gob goe gog gok goo gor gos gra grb gre grg grk gro grr grs gsa gsb gse gsg gsk gso gsr gss ka- kaa kab kae kag kak kao kar kas kba kbb kbe kbk kbo kbr kbs ke- kea keb kee keg kek keo ker kes kga kgb kgo kgs kkb kke kkk kkr kks koa kob koe kog kok koo kor kos kra krg krk kro krr krs ksa ksb kse ksg ksk kso ksr kss oaa oab oae oag oak oao oar oas ob- oba obb obe obg obk obo obr obs oea oeb oee oeg oeo oer oes oga oge ogg ogo ogs oka okb oke okg okk oko okr oks oo- ooa oob oog ook ooo oor oos or- ora orb ore org ork oro orr ors os- osa osb ose osg osk oso osr oss ra- raa rab rae rag rak rao rar ras rba rbb rbe rbg rbk rbo rbr rbs re- rea reb ree reg rek reo rer res rga rgb rge rgg rgk rgo rgr rgs rkb rke rkg rkk rko rks roa rob roe rog rok roo ror ros rra rrb rrg rrk rrr rrs rsa rsb rse rsg rsk rso rsr rss saa sab sae sag sak sao sar sas sba sbb sbe sbg sbk sbo sbr sbs se- sea seb see seg sek seo ser ses sga sgb sge sgg sgk sgo sgr sgs sk- ska skb ske skg skk sko skr sks soa sob soe sog sok soo sor sos sr- sra srb sre srg srk sro srr srs ss- ssa ssb sse ssg ssk sso ssr sss