-er a-a a-b a-t aaa aab aae aan aao aar aat aav ab- aba abb abe abn abo abr abt abv aea aeb aee aen aeo aer aet aev an- ana anb ane ann ano anr ant anv aoa aob aoe aon aoo aor aot aov ar- ara arb are arn aro arr art arv at- ata atb ate atn ato atr att atv av- ava avb ave avn avo avr avt baa bab bae ban bao bar bat bav bba bbb bbe bbn bbo bbr bbt be- bea beb bee ben beo ber bet bev bna bnb bne bnn bno bnr bnt bnv boa bob boe bon boo bor bot bov bra brb bre brn bro brr brt brv bta btb bte btn bto btr btt btv bva bvb bve bvn bvo bvr bvt bvv eaa eab eae ean eao ear eat eav eba ebb ebe ebn ebo ebr ebt ebv eea eeb eee een eeo eer eet eev en- ena enb ene enn eno enr ent env eo- eoa eob eoe eon eoo eor eot era erb ere ern ero err ert erv eta etb ete etn eto etr ett etv eva evb eve evn evo evr evt evv naa nab nae nan nao nar nat nav nba nbb nbe nbn nbo nbr nbt nbv ne- nea neb nee nen neo ner net nev nna nnb nne nnn nno nnt nnv no- noa nob noe non noo nor not nov nra nrb nre nrn nro nrr nrt nrv nta ntb nte ntn nto ntr ntt ntv nva nvb nve nvn nvt nvv oaa oab oae oan oao oar oat oav ob- oba obb obe obn obo obr obt obv oea oeb oee oen oeo oer oet on- ona onb one onn ono onr ont oo- ooa oob oon ooo oor oot oov or- ora orb ore orn oro orr ort orv ot- ota otb ote otn oto otr ott otv ov- ova ovb ove ovo ovv ra- raa rab rae ran rao rar rat rav rba rbb rbe rbn rbo rbr rbt re- rea reb ree ren reo rer ret rev rna rnb rnn rno rnr rnt rnv roa rob roe ron roo ror rot rov rra rrb rrn rrr rrt rta rtb rte rtn rto rtr rtt rtv rva rvb rve rvn rvo rvr rvt rvv taa tab tae tan tao tar tat tav tba tbb tbe tbn tbo tbr tbt tbv te- tea teb tee ten teo ter tet tev tna tnb tne tnn tno tnr tnt to- toa tob toe ton too tor tot tov tra trb tre trn tro trr trt trv tta ttb tte ttn tto ttr ttt ttv tva tvb tve tvn tvo tvr tvt v-a v-e vaa vab vae van vao var vat vav vba vbo vbr vbv vea veb vee ven veo ver vet vn- vna vno vnr vnv voa vob voe von voo vor vot vov vra vrb vre vrn vrr vrt vta vtb vte vto vtr vtt vtv vva vvb vvo vvr vvt vvv