a-a a-b aaa aab aag aah aao ab- aba abb abg abh abo ag- aga agb agg agh ago aha ahb ahg ahh aho aoa aob aog aoh aoo baa bab bag bah bao bba bbb bbg bbh bbo bga bgb bgg bgh bgo bha bhb bhg bhh bho boa bob bog boh boo gaa gab gag gah gao gba gbg gbh gbo gga ggb ggg ggh ggo gha ghb ghg ghh gho goa gob gog goh goo haa hab hag hah hao hba hbb hbg hbh hbo hga hgb hgg hgh hgo hha hhb hhg hhh hho hoa hob hog hoh hoo oaa oab oag oah oao ob- oba obb obg obh obo oga ogg ogh ogo oha ohg ohh oho oo- ooa oob oog ooh ooo