-er a-a a-b aaa aab aae aag aak aan aar aas ab- aba abb abe abg abk abn abr abs aea aeb aee aeg aek aen aer aes ag- aga agb age agg agk agn agr ags aka akb ake akg akk akn akr aks an- ana anb ane ang ank ann anr ans ar- ara arb are arg ark arn arr ars as- asa asb ase asg ask asn asr ass baa bab bae bag bak ban bar bas bba bbb bbe bbg bbk bbn bbr bbs be- bea beb bee beg bek ben ber bes bga bgb bge bgg bgk bgn bgr bgs bka bkb bke bkg bkk bkn bkr bks bna bnb bne bng bnk bnn bnr bns bra brb bre brg brk brn brr brs bsa bsb bse bsg bsk bsn bsr bss eaa eab eae eag eak ean ear eas eba ebb ebe ebg ebk ebn ebr ebs eea eeb eee eeg eek een eer ees ega egb ege egg egn egr egs eka ekb eke ekg ekr eks en- ena enb ene eng enk enn enr ens era erb ere erg erk ern err ers es- esa esb ese esg esk esn esr ess gaa gab gae gag gak gan gar gas gba gbe gbg gbk gbn gbr gbs ge- gea geb gee geg gek gen ger ges gga ggb ggg ggn ggr ggs gka gkb gkn gks gna gnb gne gnn gnr gns gra grb gre grg grk grn grr grs gsa gsb gse gsg gsk gsn gsr gss ka- kaa kab kae kag kak kan kar kas kba kbb kbe kbk kbn kbr kbs ke- kea keb kee keg kek ken ker kes kga kgb kgs kkb kke kkk kkn kkr kks kn- kna kne kng knk knn knr kra krg krk krn krr krs ksa ksb kse ksg ksk ksn ksr kss naa nab nae nag nak nan nar nas nba nbb nbe nbg nbk nbn nbr nbs ne- nea neb nee neg nek nen ner nes nga ngb nge ngg ngk ngn ngs nka nke nkk nkn nkr nks nna nnb nne nng nnk nnn nns nra nrb nre nrg nrk nrn nrr nrs nsa nsb nse nsg nsk nsn nsr nss ra- raa rab rae rag rak ran rar ras rba rbb rbe rbg rbk rbn rbr rbs re- rea reb ree reg rek ren rer res rga rgb rge rgg rgk rgn rgr rgs rkb rke rkg rkk rks rna rnb rng rnn rnr rns rra rrb rrg rrk rrn rrr rrs rsa rsb rse rsg rsk rsn rsr rss saa sab sae sag sak san sar sas sba sbb sbe sbg sbk sbn sbr sbs se- sea seb see seg sek sen ser ses sga sgb sge sgg sgk sgn sgr sgs sk- ska skb ske skg skk skr sks sna snb sne sng snk snn snr sns sr- sra srb sre srg srk srn srr srs ss- ssa ssb sse ssg ssk ssn ssr sss