a-a a-b aaa aab aae aaf aak aam aao aas ab- aba abb abe abf abk abm abo abs aea aeb aee aef aek aem aeo aes af- afa afb afe aff afk afm afo afs aka akb ake akk akm ako aks ama amb ame amf amk amm amo ams aoa aob aoe aof aok aom aoo aos as- asa asb ase asf ask asm aso ass baa bab bae baf bak bam bao bas bba bbb bbe bbf bbk bbm bbo bbs be- bea beb bee bef bek bem beo bes bfa bfb bfe bff bfm bfo bfs bka bkb bke bkf bkk bkm bko bks bma bmb bme bmf bmk bmm bmo bms boa bob boe bof bok bom boo bos bsa bsb bse bsf bsk bsm bso bss eaa eab eae eaf eak eam eao eas eba ebb ebe ebf ebk ebm ebo ebs eea eeb eee eef eek eem eeo ees ef- efa efb efe eff efm efo efs eka ekb eke ekf eko eks em- ema emb eme emf emk emm emo ems eo- eoa eob eoe eof eok eom eoo eos es- esa esb ese esf esk esm eso ess faa fab fae faf fak fam fao fas fba fbb fbe fbf fbk fbm fbo fbs fea feb fee fef fek fem feo fes ffa ffe fff ffk ffm ffo ffs fka fkb fkf fkk fkm fma fmb fme fmf fmm fmo fms foa fob foe fof fok fom foo fos fsa fsb fse fsf fsk fsm fso fss ka- kaa kab kae kaf kak kam kao kas kba kbb kbe kbf kbk kbm kbo kbs ke- kea keb kee kef kek kem keo kes kfa kff kfm kfo kfs kkb kke kkk kkm kks kma kmb kme kmf kmk kmm kmo kms koa kob koe kof kok kom koo kos ksa ksb kse ksf ksk ksm kso kss m-f m-o maa mab mae maf mak mam mao mas mba mbb mbe mbf mbk mbm mbo mbs mea meb mee mef mek mem meo mes mfa mfb mfe mff mfm mfo mfs mka mkb mke mkk mkm mko mks mma mmb mme mmf mmk mmm mmo mms moa mob moe mof mok mom moo mos msa msb mse msf msk msm mso mss oaa oab oae oaf oak oam oao oas ob- oba obb obe obf obk obm obo obs oea oeb oee oef oem oeo oes of- ofa ofb ofe off ofm ofo ofs oka okb oke okk oko oks om- oma omb ome omf omm omo oms oo- ooa oob oof ook oom ooo oos os- osa osb ose osf osk osm oso oss saa sab sae saf sak sam sao sas sba sbb sbe sbf sbk sbm sbo sbs se- sea seb see sef sek sem seo ses sfa sfb sfe sff sfk sfm sfo sfs sk- ska skb ske skf skk skm sko sks sma smb sme smf smk smm smo sms soa sob soe sof sok som soo sos ss- ssa ssb sse ssf ssk ssm sso sss