a-a a-b a-c aaa aab aac aaf aak aam aao ab- aba abb abc abf abk abm abo ac- aca acb acc acf ack acm aco af- afa afb afc aff afk afm afo aka akb akc akk akm ako ama amb amc amf amk amm amo aoa aob aoc aof aok aom aoo baa bab bac baf bak bam bao bba bbb bbc bbf bbk bbm bbo bca bcb bcc bcf bck bcm bco bfa bfb bfc bff bfm bfo bka bkb bkc bkf bkk bkm bko bma bmb bmc bmf bmk bmm bmo boa bob boc bof bok bom boo c-- caa cab cac caf cak cam cao cba cbb cbc cbf cbk cbm cbo cca ccb ccc ccf cck ccm cco cfa cfb cfc cff cfk cfm cfo cka ckb ckc ckm cko cma cmb cmc cmf cmk cmm cmo co- coa cob coc cof cok com coo faa fab fac faf fak fam fao fba fbb fbc fbf fbk fbm fbo fca fcb fcc fcf fck fcm fco ffa ffc fff ffk ffm ffo fka fkb fkc fkf fkk fkm fma fmb fmc fmf fmm fmo foa fob foc fof fok fom foo ka- kaa kab kac kaf kak kam kao kba kbb kbc kbf kbk kbm kbo kca kcb kcc kck kcm kfa kfc kff kfm kfo kkb kkc kkk kkm kma kmb kmc kmf kmk kmm kmo koa kob koc kof kok kom koo m-f m-o maa mab mac maf mak mam mao mba mbb mbc mbf mbk mbm mbo mc- mca mcb mcc mcf mck mcm mco mfa mfb mfc mff mfm mfo mka mkb mkc mkk mkm mko mma mmb mmc mmf mmk mmm mmo moa mob moc mof mok mom moo oaa oab oac oaf oak oam oao ob- oba obb obc obf obk obm obo oc- oca ocb occ ocf ock ocm oco of- ofa ofb ofc off ofm ofo oka okb okc okk oko om- oma omb omc omf omm omo oo- ooa oob ooc oof ook oom ooo