-er a-a a-b a-c aaa aab aac aae aam aao aar aas ab- aba abb abc abe abm abo abr abs ac- aca acb acc ace acm aco acr acs aea aeb aec aee aem aeo aer aes ama amb amc ame amm amo amr ams aoa aob aoc aoe aom aoo aor aos ar- ara arb arc are arm aro arr ars as- asa asb asc ase asm aso asr ass baa bab bac bae bam bao bar bas bba bbb bbc bbe bbm bbo bbr bbs bca bcb bcc bce bcm bco bcr bcs be- bea beb bec bee bem beo ber bes bma bmb bmc bme bmm bmo bmr bms boa bob boc boe bom boo bor bos bra brb bre brm bro brr brs bsa bsb bsc bse bsm bso bsr bss c-- caa cab cac cae cam cao car cas cba cbb cbc cbe cbm cbo cbr cbs cca ccb ccc cce ccm cco ccr ccs ce- cea ceb cec cee cem ceo cer ces cma cmb cmc cme cmm cmo cmr cms co- coa cob coc coe com coo cor cos cra crb crc cre crm cro crr crs csa csb csc cse csm cso csr css eaa eab eac eae eam eao ear eas eba ebb ebc ebe ebm ebo ebr ebs ec- eca ecb ecc ece ecm eco ecr ecs eea eeb eec eee eem eeo eer ees em- ema emb emc eme emm emo emr ems eo- eoa eob eoc eoe eom eoo eor eos era erb erc ere erm ero err ers es- esa esb esc ese esm eso esr ess m-o m-r maa mab mac mae mam mao mar mas mba mbb mbc mbe mbm mbo mbr mbs mc- mca mcb mcc mce mcm mco mcr mcs mea meb mec mee mem meo mer mes mma mmb mmc mme mmm mmo mmr mms moa mob moc moe mom moo mor mos mra mrb mrc mre mrm mro mrr mrs msa msb msc mse msm mso msr mss oaa oab oac oae oam oao oar oas ob- oba obb obc obe obm obo obr obs oc- oca ocb occ ocm oco ocr ocs oea oeb oec oee oem oeo oer oes om- oma omb omc ome omm omo omr oms oo- ooa oob ooc oom ooo oor oos or- ora orb orc ore orm oro orr ors os- osa osb osc ose osm oso osr oss ra- raa rab rac rae ram rao rar ras rba rbb rbc rbe rbm rbo rbr rbs rca rcb rcc rce rcm rco rcr rcs re- rea reb rec ree rem reo rer res rma rmb rmc rme rmm rmo rmr rms roa rob roc roe rom roo ror ros rra rrb rrc rrm rrr rrs rsa rsb rsc rse rsm rso rsr rss saa sab sac sae sam sao sar sas sba sbb sbc sbe sbm sbo sbr sbs sca scb scc sce scm sco scr scs se- sea seb sec see sem seo ser ses sma smb smc sme smm smo smr sms soa sob soc soe som soo sor sos sr- sra srb src sre srm sro srr srs ss- ssa ssb ssc sse ssm sso ssr sss