a-a a-b a-t aaa aab aag aar aas aat ab- aba abb abg abr abs abt ag- aga agb agg agr ags agt ar- ara arb arg arr ars art as- asa asb asg asr ass ast at- ata atb atg atr ats att baa bab bag bar bas bat bba bbb bbg bbr bbs bbt bga bgb bgg bgr bgs bgt bra brb brg brr brs brt bsa bsb bsg bsr bss bst bta btb btg btr bts btt gaa gab gag gar gas gat gba gbg gbr gbs gbt gga ggb ggg ggr ggs ggt gra grb grg grr grs grt gsa gsb gsg gsr gss gst gta gtb gtg gtr gts gtt ra- raa rab rag rar ras rat rba rbb rbg rbr rbs rbt rga rgb rgg rgr rgs rgt rra rrb rrg rrr rrs rrt rsa rsb rsg rsr rss rst rta rtb rtg rtr rts rtt saa sab sag sar sas sat sba sbb sbg sbr sbs sbt sga sgb sgg sgr sgs sgt sr- sra srb srg srr srs srt ss- ssa ssb ssg ssr sss sst sta stb stg str sts stt taa tab tag tar tas tat tba tbb tbg tbr tbs tbt tga tgb tgg tgr tgs tgt tra trb trg trr trs trt tsa tsb tsg tsr tss tst tta ttb ttg ttr tts ttt