-er a-a a-b aaa aab aad aae aaf aak aao aar ab- aba abb abd abe abf abk abo abr ad- ada adb add ade adf adk ado adr aea aeb aed aee aef aek aeo aer af- afa afb afd afe aff afk afo afr aka akb akd ake akk ako akr aoa aob aod aoe aof aok aoo aor ar- ara arb ard are arf ark aro arr baa bab bad bae baf bak bao bar bba bbb bbd bbe bbf bbk bbo bbr bda bdb bdd bde bdf bdk bdo bdr be- bea beb bed bee bef bek beo ber bfa bfb bfd bfe bff bfo bfr bka bkb bke bkf bkk bko bkr boa bob bod boe bof bok boo bor bra brb brd bre brf brk bro brr daa dab dad dae daf dak dao dar dba dbb dbd dbe dbf dbk dbo dbr dda ddb ddd dde ddf ddk ddo ddr de- dea deb ded dee def dek deo der dfa dfb dfd dfe dff dfk dfo dfr dka dkb dke dkk dko dkr doa dob dod doe dof dok doo dor dra drb drd dre drk dro drr eaa eab ead eae eaf eak eao ear eba ebb ebd ebe ebf ebk ebo ebr ed- eda edb edd ede edf edk edo edr eea eeb eed eee eef eek eeo eer ef- efa efb efd efe eff efo efr eka ekb ekd eke ekf eko ekr eo- eoa eob eod eoe eof eok eoo eor era erb erd ere erf erk ero err faa fab fad fae faf fak fao far fba fbb fbd fbe fbf fbk fbo fbr fda fdb fdd fde fdf fdk fdo fdr fea feb fed fee fef fek feo fer ffa ffd ffe fff ffk ffo ffr fka fkb fkf fkk foa fob foe fof fok foo for fra frb frd fre frf frk fro frr ka- kaa kab kad kae kaf kak kao kar kba kbb kbd kbe kbf kbk kbo kbr kda kdb kde kdf kdk kdo kdr ke- kea keb ked kee kef kek keo ker kfa kfd kff kfo kkb kke kkk kkr koa kob kod koe kof kok koo kor kra krd krf krk kro krr oaa oab oad oae oaf oak oao oar ob- oba obb obd obe obf obk obo obr oda odb odd ode odf odo odr oea oeb oed oee oef oeo oer of- ofa ofb ofd ofe off ofo ofr oka okb okd oke okk oko okr oo- ooa oob ood oof ook ooo oor or- ora orb ord ore orf ork oro orr ra- raa rab rad rae raf rak rao rar rba rbb rbd rbe rbf rbk rbo rbr rda rdb rdd rde rdf rdo rdr re- rea reb red ree ref rek reo rer rfa rfb rfd rfe rff rfk rfo rfr rkb rke rkf rkk rko roa rob rod roe rof rok roo ror rra rrb rrd rrf rrk rrr