a-a a-c a-z aaa aac aaf aak aao aaz ac- aca acc acf ack aco acz af- afa afc aff afk afo afz aka akc akk ako aoa aoc aof aok aoo az- aza azf azo azz c-- caa cac caf cak cao caz cca ccc ccf cck cco ccz cfa cfc cff cfk cfo cfz cka ckc cko co- coa coc cof cok coo coz cz- czc czk czo faa fac faf fak fao faz fca fcc fcf fck fco fcz ffa ffc fff ffk ffo ffz fka fkc fkf fkk foa foc fof fok foo foz k-z ka- kaa kac kaf kak kao kaz kca kcc kck kfa kfc kff kfo kkc kkk koa koc kof kok koo koz kzo oaa oac oaf oak oao oc- oca occ ocf ock oco ocz of- ofa ofc off ofo ofz oka okc okk oko oo- ooa ooc oof ook ooo oza ozo ozz zaa zac zaf zak zao zaz zco zfa zfc zka zo- zoa zoc zof zok zoo zzz