a-a a-b a-c aaa aab aac aag aao aas ab- aba abb abc abg abo abs ac- aca acb acc acg aco acs ag- aga agb agc agg ago ags aoa aob aoc aog aoo aos as- asa asb asc asg aso ass baa bab bac bag bao bas bba bbb bbc bbg bbo bbs bca bcb bcc bcg bco bcs bga bgb bgc bgg bgo bgs boa bob boc bog boo bos bsa bsb bsc bsg bso bss c-- caa cab cac cag cao cas cba cbb cbc cbg cbo cbs cca ccb ccc ccg cco ccs cga cgb cgc cgg cgo cgs co- coa cob coc cog coo cos csa csb csc csg cso css gaa gab gac gag gao gas gba gbc gbg gbo gbs gca gcb gcc gcg gco gcs gga ggb ggc ggg ggo ggs goa gob goc gog goo gos gsa gsb gsc gsg gso gss oaa oab oac oag oao oas ob- oba obb obc obg obo obs oc- oca ocb occ ocg oco ocs oga ogc ogg ogo ogs oo- ooa oob ooc oog ooo oos os- osa osb osc osg oso oss saa sab sac sag sao sas sba sbb sbc sbg sbo sbs sca scb scc scg sco scs sga sgb sgc sgg sgo sgs soa sob soc sog soo sos ss- ssa ssb ssc ssg sso sss