a-a a-b a-c aaa aab aac aag aar aas ab- aba abb abc abg abr abs ac- aca acb acc acg acr acs ag- aga agb agc agg agr ags ar- ara arb arc arg arr ars as- asa asb asc asg asr ass baa bab bac bag bar bas bba bbb bbc bbg bbr bbs bca bcb bcc bcg bcr bcs bga bgb bgc bgg bgr bgs bra brb brg brr brs bsa bsb bsc bsg bsr bss c-- caa cab cac cag car cas cba cbb cbc cbg cbr cbs cca ccb ccc ccg ccr ccs cga cgb cgc cgg cgr cgs cra crb crc crg crr crs csa csb csc csg csr css gaa gab gac gag gar gas gba gbc gbg gbr gbs gca gcb gcc gcg gcr gcs gga ggb ggc ggg ggr ggs gra grb grc grg grr grs gsa gsb gsc gsg gsr gss ra- raa rab rac rag rar ras rba rbb rbc rbg rbr rbs rca rcb rcc rcg rcr rcs rga rgb rgc rgg rgr rgs rra rrb rrc rrg rrr rrs rsa rsb rsc rsg rsr rss saa sab sac sag sar sas sba sbb sbc sbg sbr sbs sca scb scc scg scr scs sga sgb sgc sgg sgr sgs sr- sra srb src srg srr srs ss- ssa ssb ssc ssg ssr sss