a-a a-b a-c aaa aab aac aag aah aak aao ab- aba abb abc abg abh abk abo ac- aca acb acc acg ach ack aco ag- aga agb agc agg agh agk ago aha ahb ahc ahg ahh ahk aho aka akb akc akg akh akk ako aoa aob aoc aog aoh aok aoo baa bab bac bag bah bak bao bba bbb bbc bbg bbh bbk bbo bca bcb bcc bcg bch bck bco bga bgb bgc bgg bgh bgk bgo bha bhb bhc bhg bhh bhk bho bka bkb bkc bkg bkk bko boa bob boc bog boh bok boo c-- caa cab cac cag cah cak cao cba cbb cbc cbg cbh cbk cbo cca ccb ccc ccg cch cck cco cga cgb cgc cgg cgh cgo ch- cha chb chc chg chh chk cho cka ckb ckc ckh cko co- coa cob coc cog coh cok coo gaa gab gac gag gah gak gao gba gbc gbg gbh gbk gbo gca gcb gcc gcg gch gck gco gga ggb ggc ggg ggh ggo gha ghb ghc ghg ghh gho gka gkb gkh gko goa gob goc gog goh gok goo haa hab hac hag hah hak hao hba hbb hbc hbg hbh hbk hbo hca hcb hcc hcg hch hck hco hga hgb hgc hgg hgh hgk hgo hha hhb hhc hhg hhh hhk hho hka hkb hkg hkh hkk hko hoa hob hoc hog hoh hok hoo ka- kaa kab kac kag kah kak kao kba kbb kbc kbh kbk kbo kca kcb kcc kcg kch kck kga kgb kgc kgh kgo kha khh khk kho kkb kkc kkh kkk koa kob koc kog koh kok koo oaa oab oac oag oah oak oao ob- oba obb obc obg obh obk obo oc- oca ocb occ ocg och ock oco oga ogc ogg ogh ogo oha ohc ohg ohh oho oka okb okc okg okk oko oo- ooa oob ooc oog ooh ook ooo