a-a a-b a-z aaa aab aak aan aao aaz ab- aba abb abk abn abo abz aka akb akk akn ako an- ana anb ank ann ano anz aoa aob aok aon aoo az- aza azb azn azo azz baa bab bak ban bao baz bba bbb bbk bbn bbo bka bkb bkk bkn bko bna bnb bnk bnn bno bnz boa bob bok bon boo boz bza bzn bzo bzz k-z ka- kaa kab kak kan kao kaz kba kbb kbk kbn kbo kbz kkb kkk kkn kn- kna knk knn kno koa kob kok kon koo koz kzo naa nab nak nan nao naz nba nbb nbk nbn nbo nka nkk nkn nko nna nnb nnk nnn nno nnz no- noa nob nok non noo noz nzb nzo nzz oaa oab oak oan oao ob- oba obb obk obn obo oka okb okk oko on- ona onb onk onn ono oo- ooa oob ook oon ooo oza ozo ozz zaa zab zak zan zao zaz zbb zka znn zno zo- zoa zob zok zon zoo zzz