a-a a-b a-c a-z aaa aab aac aag aao aas aaz ab- aba abb abc abg abo abs abz ac- aca acb acc acg aco acs acz ag- aga agb agc agg ago ags agz aoa aob aoc aog aoo aos as- asa asb asc asg aso ass asz az- aza azb azg azo azs azz baa bab bac bag bao bas baz bba bbb bbc bbg bbo bbs bca bcb bcc bcg bco bcs bcz bga bgb bgc bgg bgo bgs bgz boa bob boc bog boo bos boz bsa bsb bsc bsg bso bss bza bzo bzs bzz c-- caa cab cac cag cao cas caz cba cbb cbc cbg cbo cbs cbz cca ccb ccc ccg cco ccs ccz cga cgb cgc cgg cgo cgs co- coa cob coc cog coo cos coz csa csb csc csg cso css csz cz- czc czo gaa gab gac gag gao gas gaz gba gbc gbg gbo gbs gbz gca gcb gcc gcg gco gcs gga ggb ggc ggg ggo ggs ggz goa gob goc gog goo gos goz gsa gsb gsc gsg gso gss gza gzo oaa oab oac oag oao oas ob- oba obb obc obg obo obs oc- oca ocb occ ocg oco ocs ocz oga ogc ogg ogo ogs oo- ooa oob ooc oog ooo oos os- osa osb osc osg oso oss oza ozo ozs ozz saa sab sac sag sao sas saz sba sbb sbc sbg sbo sbs sca scb scc scg sco scs sga sgb sgc sgg sgo sgs soa sob soc sog soo sos soz ss- ssa ssb ssc ssg sso sss ssz sza z-g zaa zab zac zag zao zas zaz zbb zbc zbs zco zcs zgb zgg zgs zo- zoa zob zoc zog zoo zos zsa zsg zsz zzs zzz