-er a-a a-b aaa aab aae aaf aak aam aao aar ab- aba abb abe abf abk abm abo abr aea aeb aee aef aek aem aeo aer af- afa afb afe aff afk afm afo afr aka akb ake akk akm ako akr ama amb ame amf amk amm amo amr aoa aob aoe aof aok aom aoo aor ar- ara arb are arf ark arm aro arr baa bab bae baf bak bam bao bar bba bbb bbe bbf bbk bbm bbo bbr be- bea beb bee bef bek bem beo ber bfa bfb bfe bff bfm bfo bfr bka bkb bke bkf bkk bkm bko bkr bma bmb bme bmf bmk bmm bmo bmr boa bob boe bof bok bom boo bor bra brb bre brf brk brm bro brr eaa eab eae eaf eak eam eao ear eba ebb ebe ebf ebk ebm ebo ebr eea eeb eee eef eek eem eeo eer ef- efa efb efe eff efm efo efr eka ekb eke ekf eko ekr em- ema emb eme emf emk emm emo emr eo- eoa eob eoe eof eok eom eoo eor era erb ere erf erk erm ero err faa fab fae faf fak fam fao far fba fbb fbe fbf fbk fbm fbo fbr fea feb fee fef fek fem feo fer ffa ffe fff ffk ffm ffo ffr fka fkb fkf fkk fkm fma fmb fme fmf fmm fmo fmr foa fob foe fof fok fom foo for fra frb fre frf frk frm fro frr ka- kaa kab kae kaf kak kam kao kar kba kbb kbe kbf kbk kbm kbo kbr ke- kea keb kee kef kek kem keo ker kfa kff kfm kfo kkb kke kkk kkm kkr kma kmb kme kmf kmk kmm kmo koa kob koe kof kok kom koo kor kra krf krk kro krr m-f m-o m-r maa mab mae maf mak mam mao mar mba mbb mbe mbf mbk mbm mbo mbr mea meb mee mef mek mem meo mer mfa mfb mfe mff mfm mfo mfr mka mkb mke mkk mkm mko mkr mma mmb mme mmf mmk mmm mmo mmr moa mob moe mof mok mom moo mor mra mrb mre mrf mrk mrm mro mrr oaa oab oae oaf oak oam oao oar ob- oba obb obe obf obk obm obo obr oea oeb oee oef oem oeo oer of- ofa ofb ofe off ofm ofo ofr oka okb oke okk oko okr om- oma omb ome omf omm omo omr oo- ooa oob oof ook oom ooo oor or- ora orb ore orf ork orm oro orr ra- raa rab rae raf rak ram rao rar rba rbb rbe rbf rbk rbm rbo rbr re- rea reb ree ref rek rem reo rer rfa rfb rfe rff rfk rfm rfo rfr rkb rke rkf rkk rkm rko rma rmb rme rmf rmm rmo rmr roa rob roe rof rok rom roo ror rra rrb rrf rrk rrm rrr