-er a-a a-b aaa aab aad aae aak aao aar aas ab- aba abb abd abe abk abo abr abs ad- ada adb add ade adk ado adr ads aea aeb aed aee aek aeo aer aes aka akb akd ake akk ako akr aks aoa aob aod aoe aok aoo aor aos ar- ara arb ard are ark aro arr ars as- asa asb asd ase ask aso asr ass baa bab bad bae bak bao bar bas bba bbb bbd bbe bbk bbo bbr bbs bda bdb bdd bde bdk bdo bdr bds be- bea beb bed bee bek beo ber bes bka bkb bke bkk bko bkr bks boa bob bod boe bok boo bor bos bra brb brd bre brk bro brr brs bsa bsb bsd bse bsk bso bsr bss daa dab dad dae dak dao dar das dba dbb dbd dbe dbk dbo dbr dbs dda ddb ddd dde ddk ddo ddr dds de- dea deb ded dee dek deo der des dka dkb dke dkk dko dkr dks doa dob dod doe dok doo dor dos dra drb drd dre drk dro drr drs dsa dsb dsd dse dsk dso dsr dss eaa eab ead eae eak eao ear eas eba ebb ebd ebe ebk ebo ebr ebs ed- eda edb edd ede edk edo edr eds eea eeb eed eee eek eeo eer ees eka ekb ekd eke eko ekr eks eo- eoa eob eod eoe eok eoo eor eos era erb erd ere erk ero err ers es- esa esb esd ese esk eso esr ess ka- kaa kab kad kae kak kao kar kas kba kbb kbd kbe kbk kbo kbr kbs kda kdb kde kdk kdo kdr kds ke- kea keb ked kee kek keo ker kes kkb kke kkk kkr kks koa kob kod koe kok koo kor kos kra krd krk kro krr krs ksa ksb ksd kse ksk kso ksr kss oaa oab oad oae oak oao oar oas ob- oba obb obd obe obk obo obr obs oda odb odd ode odo odr ods oea oeb oed oee oeo oer oes oka okb okd oke okk oko okr oks oo- ooa oob ood ook ooo oor oos or- ora orb ord ore ork oro orr ors os- osa osb osd ose osk oso osr oss ra- raa rab rad rae rak rao rar ras rba rbb rbd rbe rbk rbo rbr rbs rda rdb rdd rde rdo rdr rds re- rea reb red ree rek reo rer res rkb rke rkk rko rks roa rob rod roe rok roo ror ros rra rrb rrd rrk rrr rrs rsa rsb rsd rse rsk rso rsr rss saa sab sad sae sak sao sar sas sba sbb sbd sbe sbk sbo sbr sbs sda sdb sdd sde sdk sdo sdr sds se- sea seb sed see sek seo ser ses sk- ska skb skd ske skk sko skr sks soa sob sod soe sok soo sor sos sr- sra srb srd sre srk sro srr srs ss- ssa ssb ssd sse ssk sso ssr sss