a-a a-b a-c aaa aab aac aag aas ab- aba abb abc abg abs ac- aca acb acc acg acs ag- aga agb agc agg ags as- asa asb asc asg ass baa bab bac bag bas bba bbb bbc bbg bbs bca bcb bcc bcg bcs bga bgb bgc bgg bgs bsa bsb bsc bsg bss c-- caa cab cac cag cas cba cbb cbc cbg cbs cca ccb ccc ccg ccs cga cgb cgc cgg cgs csa csb csc csg css gaa gab gac gag gas gba gbc gbg gbs gca gcb gcc gcg gcs gga ggb ggc ggg ggs gsa gsb gsc gsg gss saa sab sac sag sas sba sbb sbc sbg sbs sca scb scc scg scs sga sgb sgc sgg sgs ss- ssa ssb ssc ssg sss