-er a-a a-b aaa aab aae aam aao aar aas ab- aba abb abe abm abo abr abs aea aeb aee aem aeo aer aes ama amb ame amm amo amr ams aoa aob aoe aom aoo aor aos ar- ara arb are arm aro arr ars as- asa asb ase asm aso asr ass baa bab bae bam bao bar bas bba bbb bbe bbm bbo bbr bbs be- bea beb bee bem beo ber bes bma bmb bme bmm bmo bmr bms boa bob boe bom boo bor bos bra brb bre brm bro brr brs bsa bsb bse bsm bso bsr bss eaa eab eae eam eao ear eas eba ebb ebe ebm ebo ebr ebs eea eeb eee eem eeo eer ees em- ema emb eme emm emo emr ems eo- eoa eob eoe eom eoo eor eos era erb ere erm ero err ers es- esa esb ese esm eso esr ess m-o m-r maa mab mae mam mao mar mas mba mbb mbe mbm mbo mbr mbs mea meb mee mem meo mer mes mma mmb mme mmm mmo mmr mms moa mob moe mom moo mor mos mra mrb mre mrm mro mrr mrs msa msb mse msm mso msr mss oaa oab oae oam oao oar oas ob- oba obb obe obm obo obr obs oea oeb oee oem oeo oer oes om- oma omb ome omm omo omr oms oo- ooa oob oom ooo oor oos or- ora orb ore orm oro orr ors os- osa osb ose osm oso osr oss ra- raa rab rae ram rao rar ras rba rbb rbe rbm rbo rbr rbs re- rea reb ree rem reo rer res rma rmb rme rmm rmo rmr rms roa rob roe rom roo ror ros rra rrb rrm rrr rrs rsa rsb rse rsm rso rsr rss saa sab sae sam sao sar sas sba sbb sbe sbm sbo sbr sbs se- sea seb see sem seo ser ses sma smb sme smm smo smr sms soa sob soe som soo sor sos sr- sra srb sre srm sro srr srs ss- ssa ssb sse ssm sso ssr sss