a-a a-b a-t aaa aab aag aas aat ab- aba abb abg abs abt ag- aga agb agg ags agt as- asa asb asg ass ast at- ata atb atg ats att baa bab bag bas bat bba bbb bbg bbs bbt bga bgb bgg bgs bgt bsa bsb bsg bss bst bta btb btg bts btt gaa gab gag gas gat gba gbg gbs gbt gga ggb ggg ggs ggt gsa gsb gsg gss gst gta gtb gtg gts gtt saa sab sag sas sat sba sbb sbg sbs sbt sga sgb sgg sgs sgt ss- ssa ssb ssg sss sst sta stb stg sts stt taa tab tag tas tat tba tbb tbg tbs tbt tga tgb tgg tgs tgt tsa tsb tsg tss tst tta ttb ttg tts ttt