-er a-a a-b a-c aaa aab aac aae aag aao aar aas ab- aba abb abc abe abg abo abr abs ac- aca acb acc ace acg aco acr acs aea aeb aec aee aeg aeo aer aes ag- aga agb agc age agg ago agr ags aoa aob aoc aoe aog aoo aor aos ar- ara arb arc are arg aro arr ars as- asa asb asc ase asg aso asr ass baa bab bac bae bag bao bar bas bba bbb bbc bbe bbg bbo bbr bbs bca bcb bcc bce bcg bco bcr bcs be- bea beb bec bee beg beo ber bes bga bgb bgc bge bgg bgo bgr bgs boa bob boc boe bog boo bor bos bra brb bre brg bro brr brs bsa bsb bsc bse bsg bso bsr bss c-- caa cab cac cae cag cao car cas cba cbb cbc cbe cbg cbo cbr cbs cca ccb ccc cce ccg cco ccr ccs ce- cea ceb cec cee ceg ceo cer ces cga cgb cgc cge cgg cgo cgr cgs co- coa cob coc coe cog coo cor cos cra crb crc cre crg cro crr crs csa csb csc cse csg cso csr css eaa eab eac eae eag eao ear eas eba ebb ebc ebe ebg ebo ebr ebs ec- eca ecb ecc ece ecg eco ecr ecs eea eeb eec eee eeg eeo eer ees ega egb egc ege egg ego egr egs eo- eoa eob eoc eoe eog eoo eor eos era erb erc ere erg ero err ers es- esa esb esc ese esg eso esr ess gaa gab gac gae gag gao gar gas gba gbc gbe gbg gbo gbr gbs gca gcb gcc gce gcg gco gcr gcs ge- gea geb gec gee geg geo ger ges gga ggb ggc ggg ggo ggr ggs goa gob goc goe gog goo gor gos gra grb grc gre grg gro grr grs gsa gsb gsc gse gsg gso gsr gss oaa oab oac oae oag oao oar oas ob- oba obb obc obe obg obo obr obs oc- oca ocb occ ocg oco ocr ocs oea oeb oec oee oeg oeo oer oes oga ogc oge ogg ogo ogs oo- ooa oob ooc oog ooo oor oos or- ora orb orc ore org oro orr ors os- osa osb osc ose osg oso osr oss ra- raa rab rac rae rag rao rar ras rba rbb rbc rbe rbg rbo rbr rbs rca rcb rcc rce rcg rco rcr rcs re- rea reb rec ree reg reo rer res rga rgb rgc rge rgg rgo rgr rgs roa rob roc roe rog roo ror ros rra rrb rrc rrg rrr rrs rsa rsb rsc rse rsg rso rsr rss saa sab sac sae sag sao sar sas sba sbb sbc sbe sbg sbo sbr sbs sca scb scc sce scg sco scr scs se- sea seb sec see seg seo ser ses sga sgb sgc sge sgg sgo sgr sgs soa sob soc soe sog soo sor sos sr- sra srb src sre srg sro srr srs ss- ssa ssb ssc sse ssg sso ssr sss