-er a-a a-b a-c aaa aab aac aae aak aam aao aar aas ab- aba abb abc abe abk abm abo abr abs ac- aca acb acc ace ack acm aco acr acs aea aeb aec aee aek aem aeo aer aes aka akb akc ake akk akm ako akr aks ama amb amc ame amk amm amo amr ams aoa aob aoc aoe aok aom aoo aor aos ar- ara arb arc are ark arm aro arr ars as- asa asb asc ase ask asm aso asr ass baa bab bac bae bak bam bao bar bas bba bbb bbc bbe bbk bbm bbo bbr bbs bca bcb bcc bce bck bcm bco bcr bcs be- bea beb bec bee bek bem beo ber bes bka bkb bkc bke bkk bkm bko bkr bks bma bmb bmc bme bmk bmm bmo bmr bms boa bob boc boe bok bom boo bor bos bra brb bre brk brm bro brr brs bsa bsb bsc bse bsk bsm bso bsr bss c-- caa cab cac cae cak cam cao car cas cba cbb cbc cbe cbk cbm cbo cbr cbs cca ccb ccc cce cck ccm cco ccr ccs ce- cea ceb cec cee cek cem ceo cer ces cka ckb ckc ckm cko cks cma cmb cmc cme cmk cmm cmo cmr cms co- coa cob coc coe cok com coo cor cos cra crb crc cre crk crm cro crr crs csa csb csc cse csk csm cso csr css eaa eab eac eae eak eam eao ear eas eba ebb ebc ebe ebk ebm ebo ebr ebs ec- eca ecb ecc ece eck ecm eco ecr ecs eea eeb eec eee eek eem eeo eer ees eka ekb ekc eke eko ekr eks em- ema emb emc eme emk emm emo emr ems eo- eoa eob eoc eoe eok eom eoo eor eos era erb erc ere erk erm ero err ers es- esa esb esc ese esk esm eso esr ess ka- kaa kab kac kae kak kam kao kar kas kba kbb kbc kbe kbk kbm kbo kbr kbs kca kcb kcc kce kck kcm kcr kcs ke- kea keb kec kee kek kem keo ker kes kkb kkc kke kkk kkm kkr kks kma kmb kmc kme kmk kmm kmo kms koa kob koc koe kok kom koo kor kos kra krc krk kro krr krs ksa ksb ksc kse ksk ksm kso ksr kss m-o m-r maa mab mac mae mak mam mao mar mas mba mbb mbc mbe mbk mbm mbo mbr mbs mc- mca mcb mcc mce mck mcm mco mcr mcs mea meb mec mee mek mem meo mer mes mka mkb mkc mke mkk mkm mko mkr mks mma mmb mmc mme mmk mmm mmo mmr mms moa mob moc moe mok mom moo mor mos mra mrb mrc mre mrk mrm mro mrr mrs msa msb msc mse msk msm mso msr mss oaa oab oac oae oak oam oao oar oas ob- oba obb obc obe obk obm obo obr obs oc- oca ocb occ ock ocm oco ocr ocs oea oeb oec oee oem oeo oer oes oka okb okc oke okk oko okr oks om- oma omb omc ome omm omo omr oms oo- ooa oob ooc ook oom ooo oor oos or- ora orb orc ore ork orm oro orr ors os- osa osb osc ose osk osm oso osr oss ra- raa rab rac rae rak ram rao rar ras rba rbb rbc rbe rbk rbm rbo rbr rbs rca rcb rcc rce rcm rco rcr rcs re- rea reb rec ree rek rem reo rer res rkb rkc rke rkk rkm rko rks rma rmb rmc rme rmm rmo rmr rms roa rob roc roe rok rom roo ror ros rra rrb rrc rrk rrm rrr rrs rsa rsb rsc rse rsk rsm rso rsr rss saa sab sac sae sak sam sao sar sas sba sbb sbc sbe sbk sbm sbo sbr sbs sca scb scc sce sck scm sco scr scs se- sea seb sec see sek sem seo ser ses sk- ska skb skc ske skk skm sko skr sks sma smb smc sme smk smm smo smr sms soa sob soc soe sok som soo sor sos sr- sra srb src sre srk srm sro srr srs ss- ssa ssb ssc sse ssk ssm sso ssr sss