-er a-a a-b aaa aab aae aaf aam aan aao aar ab- aba abb abe abf abm abn abo abr aea aeb aee aef aem aen aeo aer af- afa afb afe aff afm afn afo afr ama amb ame amf amm amn amo amr an- ana anb ane anf anm ann ano anr aoa aob aoe aof aom aon aoo aor ar- ara arb are arf arm arn aro arr baa bab bae baf bam ban bao bar bba bbb bbe bbf bbm bbn bbo bbr be- bea beb bee bef bem ben beo ber bfa bfb bfe bff bfm bfn bfo bfr bma bmb bme bmf bmm bmn bmo bmr bna bnb bne bnf bnn bno bnr boa bob boe bof bom bon boo bor bra brb bre brf brm brn bro brr eaa eab eae eaf eam ean eao ear eba ebb ebe ebf ebm ebn ebo ebr eea eeb eee eef eem een eeo eer ef- efa efb efe eff efm efo efr em- ema emb eme emf emm emn emo emr en- ena enb ene enf enm enn eno enr eo- eoa eob eoe eof eom eon eoo eor era erb ere erf erm ern ero err faa fab fae faf fam fan fao far fba fbb fbe fbf fbm fbn fbo fbr fea feb fee fef fem fen feo fer ffa ffe fff ffm ffn ffo ffr fma fmb fme fmf fmm fmn fmo fmr fna fnb fne fnf fnm fnn fnr foa fob foe fof fom fon foo for fra frb fre frf frm frn fro frr m-f m-o m-r maa mab mae maf mam man mao mar mba mbb mbe mbf mbm mbo mbr mea meb mee mef mem men meo mer mfa mfb mfe mff mfm mfn mfo mfr mma mmb mme mmf mmm mmn mmo mmr mna mnb mne mnf mnm mnn mno mnr moa mob moe mof mom mon moo mor mra mrb mre mrf mrm mrn mro mrr naa nab nae naf nam nan nao nar nba nbb nbe nbf nbm nbn nbo nbr ne- nea neb nee nef nem nen neo ner nfa nfb nfe nff nfn nfo nfr nma nmb nme nmm nmn nmo nmr nna nnb nne nnf nnm nnn nno no- noa nob noe nof nom non noo nor nra nrb nre nrf nrm nrn nro nrr oaa oab oae oaf oam oan oao oar ob- oba obb obe obf obm obn obo obr oea oeb oee oef oem oen oeo oer of- ofa ofb ofe off ofm ofn ofo ofr om- oma omb ome omf omm omn omo omr on- ona onb one onf onn ono onr oo- ooa oob oof oom oon ooo oor or- ora orb ore orf orm orn oro orr ra- raa rab rae raf ram ran rao rar rba rbb rbe rbf rbm rbn rbo rbr re- rea reb ree ref rem ren reo rer rfa rfb rfe rff rfm rfn rfo rfr rma rmb rme rmf rmm rmn rmo rmr rna rnb rnm rnn rno rnr roa rob roe rof rom ron roo ror rra rrb rrf rrm rrn rrr