a-a a-b a-c aaa aab aac aag aah aao ab- aba abb abc abg abh abo ac- aca acb acc acg ach aco ag- aga agb agc agg agh ago aha ahb ahc ahg ahh aho aoa aob aoc aog aoh aoo baa bab bac bag bah bao bba bbb bbc bbg bbh bbo bca bcb bcc bcg bch bco bga bgb bgc bgg bgh bgo bha bhb bhc bhg bhh bho boa bob boc bog boh boo c-- caa cab cac cag cah cao cba cbb cbc cbg cbh cbo cca ccb ccc ccg cch cco cga cgb cgc cgg cgh cgo ch- cha chb chc chg chh cho co- coa cob coc cog coh coo gaa gab gac gag gah gao gba gbc gbg gbh gbo gca gcb gcc gcg gch gco gga ggb ggc ggg ggh ggo gha ghb ghc ghg ghh gho goa gob goc gog goh goo haa hab hac hag hah hao hba hbb hbc hbg hbh hbo hca hcb hcc hcg hch hco hga hgb hgc hgg hgh hgo hha hhb hhc hhg hhh hho hoa hob hoc hog hoh hoo oaa oab oac oag oah oao ob- oba obb obc obg obh obo oc- oca ocb occ ocg och oco oga ogc ogg ogh ogo oha ohc ohg ohh oho oo- ooa oob ooc oog ooh ooo