a-a a-b a-z aaa aab aad aao aar aaz ab- aba abb abd abo abr abz ad- ada adb add ado adr adz aoa aob aod aoo aor ar- ara arb ard aro arr arz az- aza azb azd azo azz baa bab bad bao bar baz bba bbb bbd bbo bbr bda bdb bdd bdo bdr bdz boa bob bod boo bor boz bra brb brd bro brr brz bza bzd bzo bzr bzz daa dab dad dao dar daz dba dbb dbd dbo dbr dbz dda ddb ddd ddo ddr ddz doa dob dod doo dor doz dra drb drd dro drr drz dza dzb dzd dzo dzr oaa oab oad oao oar ob- oba obb obd obo obr oda odb odd odo odr oo- ooa oob ood ooo oor or- ora orb ord oro orr orz oza ozo ozz ra- raa rab rad rao rar raz rba rbb rbd rbo rbr rda rdb rdd rdo rdr roa rob rod roo ror roz rra rrb rrd rrr rza rzb rzo zaa zab zad zao zar zaz zbb zbr zo- zoa zob zod zoo zor zro zzr zzz