a-a a-b a-z aaa aab aak aao aas aaz ab- aba abb abk abo abs abz aka akb akk ako aks aoa aob aok aoo aos as- asa asb ask aso ass asz az- aza azb azo azs azz baa bab bak bao bas baz bba bbb bbk bbo bbs bka bkb bkk bko bks boa bob bok boo bos boz bsa bsb bsk bso bss bza bzo bzs bzz k-z ka- kaa kab kak kao kas kaz kba kbb kbk kbo kbs kbz kkb kkk kks koa kob kok koo kos koz ksa ksb ksk kso kss kzo oaa oab oak oao oas ob- oba obb obk obo obs oka okb okk oko oks oo- ooa oob ook ooo oos os- osa osb osk oso oss oza ozo ozs ozz saa sab sak sao sas saz sba sbb sbk sbo sbs sk- ska skb skk sko sks soa sob sok soo sos soz ss- ssa ssb ssk sso sss ssz sza zaa zab zak zao zas zaz zbb zbs zka zks zo- zoa zob zok zoo zos zsa zsz zzs zzz