-er a-a a-b aaa aab aae aag aak aar aas ab- aba abb abe abg abk abr abs aea aeb aee aeg aek aer aes ag- aga agb age agg agk agr ags aka akb ake akg akk akr aks ar- ara arb are arg ark arr ars as- asa asb ase asg ask asr ass baa bab bae bag bak bar bas bba bbb bbe bbg bbk bbr bbs be- bea beb bee beg bek ber bes bga bgb bge bgg bgk bgr bgs bka bkb bke bkg bkk bkr bks bra brb bre brg brk brr brs bsa bsb bse bsg bsk bsr bss eaa eab eae eag eak ear eas eba ebb ebe ebg ebk ebr ebs eea eeb eee eeg eek eer ees ega egb ege egg egr egs eka ekb eke ekg ekr eks era erb ere erg erk err ers es- esa esb ese esg esk esr ess gaa gab gae gag gak gar gas gba gbe gbg gbk gbr gbs ge- gea geb gee geg gek ger ges gga ggb ggg ggr ggs gka gkb gks gra grb gre grg grk grr grs gsa gsb gse gsg gsk gsr gss ka- kaa kab kae kag kak kar kas kba kbb kbe kbk kbr kbs ke- kea keb kee keg kek ker kes kga kgb kgs kkb kke kkk kkr kks kra krg krk krr krs ksa ksb kse ksg ksk ksr kss ra- raa rab rae rag rak rar ras rba rbb rbe rbg rbk rbr rbs re- rea reb ree reg rek rer res rga rgb rge rgg rgk rgr rgs rkb rke rkg rkk rks rra rrb rrg rrk rrr rrs rsa rsb rse rsg rsk rsr rss saa sab sae sag sak sar sas sba sbb sbe sbg sbk sbr sbs se- sea seb see seg sek ser ses sga sgb sge sgg sgk sgr sgs sk- ska skb ske skg skk skr sks sr- sra srb sre srg srk srr srs ss- ssa ssb sse ssg ssk ssr sss