-er a-a a-b aaa aab aae aag aao aar aas aax ab- aba abb abe abg abo abr abs abx aea aeb aee aeg aeo aer aes aex ag- aga agb age agg ago agr ags agx aoa aob aoe aog aoo aor aos aox ar- ara arb are arg aro arr ars arx as- asa asb ase asg aso asr ass asx ax- axa axe axo axr axs axx baa bab bae bag bao bar bas bax bba bbb bbe bbg bbo bbr bbs bbx be- bea beb bee beg beo ber bes bex bga bgb bge bgg bgo bgr bgs bgx boa bob boe bog boo bor bos box bra brb bre brg bro brr brs brx bsa bsb bse bsg bso bsr bss bsx bxb bxo bxx eaa eab eae eag eao ear eas eax eba ebb ebe ebg ebo ebr ebs ebx eea eeb eee eeg eeo eer ees eex ega egb ege egg ego egr egs egx eo- eoa eob eoe eog eoo eor eos era erb ere erg ero err ers es- esa esb ese esg eso esr ess esx ex- exa exe exo exr exs exx gaa gab gae gag gao gar gas gba gbe gbg gbo gbr gbs gbx ge- gea geb gee geg geo ger ges gex gga ggb ggg ggo ggr ggs goa gob goe gog goo gor gos gox gra grb gre grg gro grr grs grx gsa gsb gse gsg gso gsr gss gsx gxa gxs oaa oab oae oag oao oar oas oax ob- oba obb obe obg obo obr obs obx oea oeb oee oeg oeo oer oes oex oga oge ogg ogo ogs ogx oo- ooa oob oog ooo oor oos oox or- ora orb ore org oro orr ors orx os- osa osb ose osg oso osr oss osx ox- oxa oxb oxo oxx ra- raa rab rae rag rao rar ras rax rba rbb rbe rbg rbo rbr rbs rbx re- rea reb ree reg reo rer res rex rga rgb rge rgg rgo rgr rgs rgx roa rob roe rog roo ror ros rox rra rrb rrg rrr rrs rsa rsb rse rsg rso rsr rss rsx rxr rxs saa sab sae sag sao sar sas sax sba sbb sbe sbg sbo sbr sbs sbx se- sea seb see seg seo ser ses sex sga sgb sge sgg sgo sgr sgs sgx soa sob soe sog soo sor sos sox sr- sra srb sre srg sro srr srs srx ss- ssa ssb sse ssg sso ssr sss ssx sxs xaa xag xar xas xbe xbr xbx xee xeg xer xes xex xge xoa xog xoo xor xos xox xrx xsa xsb xss xxo xxx