a-a a-b a-c aaa aab aac aag aah ab- aba abb abc abg abh ac- aca acb acc acg ach ag- aga agb agc agg agh aha ahb ahc ahg ahh baa bab bac bag bah bba bbb bbc bbg bbh bca bcb bcc bcg bch bga bgb bgc bgg bgh bha bhb bhc bhg bhh c-- caa cab cac cag cah cba cbb cbc cbg cbh cca ccb ccc ccg cch cga cgb cgc cgg cgh ch- cha chb chc chg chh gaa gab gac gag gah gba gbc gbg gbh gca gcb gcc gcg gch gga ggb ggc ggg ggh gha ghb ghc ghg ghh haa hab hac hag hah hba hbb hbc hbg hbh hca hcb hcc hcg hch hga hgb hgc hgg hgh hha hhb hhc hhg hhh