a-a a-b a-z aaa aab aad aaf aao aay aaz ab- aba abb abd abf abo aby abz ad- ada adb add adf ado ady adz af- afa afb afd aff afo afy afz aoa aob aod aof aoo ay- aya ayd ayf ayo ayz az- aza azb azd azf azo azy azz baa bab bad baf bao bay baz bba bbb bbd bbf bbo bby bda bdb bdd bdf bdo bdy bdz bfa bfb bfd bff bfo bfy bfz boa bob bod bof boo boy boz by- bya byd byf byo byz bza bzd bzf bzo bzz daa dab dad daf dao day daz dba dbb dbd dbf dbo dby dbz dda ddb ddd ddf ddo ddy ddz dfa dfb dfd dff dfo dfz doa dob dod dof doo doy doz dy- dya dyb dyd dyo dyy dza dzb dzd dzo faa fab fad faf fao fay faz fba fbb fbd fbf fbo fda fdb fdd fdf fdo ffa ffd fff ffo ffy ffz foa fob fof foo foy foz fy- fya fyb fyo fyz fzd oaa oab oad oaf oao ob- oba obb obd obf obo oby oda odb odd odf odo of- ofa ofb ofd off ofo ofz oo- ooa oob ood oof ooo oya oyd oyo oza ozo ozz yaa yab yad yaf yao yay yaz ybf yby ybz yda ydo ydy yfa yfd yff yob yod yof yoo yoy yyb yyf yyy yyz yzb yzf yzy zaa zab zad zaf zao zay zaz zbb zby zdf zfa zfd zfy zo- zoa zob zod zof zoo zzy zzz