a-a a-b a-z aaa aab aad aao aaz ab- aba abb abd abo abz ad- ada adb add ado adz aoa aob aod aoo az- aza azb azd azo azz baa bab bad bao baz bba bbb bbd bbo bda bdb bdd bdo bdz boa bob bod boo boz bza bzd bzo bzz daa dab dad dao daz dba dbb dbd dbo dbz dda ddb ddd ddo ddz doa dob dod doo doz dza dzb dzd dzo oaa oab oad oao ob- oba obb obd obo oda odb odd odo oo- ooa oob ood ooo oza ozo ozz zaa zab zad zao zaz zbb zo- zoa zob zod zoo zzz