-er a-a a-b aaa aab aad aae aak aao aar aav ab- aba abb abd abe abk abo abr abv ad- ada adb add ade adk ado adr adv aea aeb aed aee aek aeo aer aev aka akb akd ake akk ako akr akv aoa aob aod aoe aok aoo aor aov ar- ara arb ard are ark aro arr arv av- ava avb avd ave avk avo avr baa bab bad bae bak bao bar bav bba bbb bbd bbe bbk bbo bbr bda bdb bdd bde bdk bdo bdr bdv be- bea beb bed bee bek beo ber bev bka bkb bke bkk bko bkr bkv boa bob bod boe bok boo bor bov bra brb brd bre brk bro brr brv bva bvb bvd bve bvk bvo bvr bvv daa dab dad dae dak dao dar dav dba dbb dbd dbe dbk dbo dbr dbv dda ddb ddd dde ddk ddo ddr de- dea deb ded dee dek deo der dev dka dkb dke dkk dko dkr doa dob dod doe dok doo dor dov dra drb drd dre drk dro drr drv dva dvb dvd dve dvk dvr eaa eab ead eae eak eao ear eav eba ebb ebd ebe ebk ebo ebr ebv ed- eda edb edd ede edk edo edr eea eeb eed eee eek eeo eer eev eka ekb ekd eke eko ekr ekv eo- eoa eob eod eoe eok eoo eor era erb erd ere erk ero err erv eva evb evd eve evo evr evv ka- kaa kab kad kae kak kao kar kav kba kbb kbd kbe kbk kbo kbr kda kdb kde kdk kdo kdr ke- kea keb ked kee kek keo ker kev kkb kke kkk kkr kkv koa kob kod koe kok koo kor kra krd krk kro krr krv kva kvb kvk kvo kvr kvv oaa oab oad oae oak oao oar oav ob- oba obb obd obe obk obo obr obv oda odb odd ode odo odr odv oea oeb oed oee oeo oer oka okb okd oke okk oko okr oo- ooa oob ood ook ooo oor oov or- ora orb ord ore ork oro orr orv ov- ova ovb ovd ove ovo ovv ra- raa rab rad rae rak rao rar rav rba rbb rbd rbe rbk rbo rbr rda rdb rdd rde rdo rdr rdv re- rea reb red ree rek reo rer rev rkb rke rkk rko rkv roa rob rod roe rok roo ror rov rra rrb rrd rrk rrr rva rvb rvd rve rvo rvr rvv v-a v-e vaa vab vad vae vak vao var vav vba vbd vbk vbo vbr vbv vdb vdd vde vdk vdo vdr vdv vea veb ved vee vek veo ver vka vkb voa vob vod voe vok voo vor vov vra vrb vrd vre vrk vrr vva vvb vvo vvr vvv