a-a a-b aaa aab aad aak aan aao ab- aba abb abd abk abn abo ad- ada adb add adk adn ado aka akb akd akk akn ako an- ana anb and ank ann ano aoa aob aod aok aon aoo baa bab bad bak ban bao bba bbb bbd bbk bbn bbo bda bdb bdd bdk bdo bka bkb bkk bkn bko bna bnb bnd bnk bnn bno boa bob bod bok bon boo daa dab dad dak dan dao dba dbb dbd dbk dbn dbo dda ddb ddd ddk ddn ddo dka dkb dkk dko dna dnb dnd dnk dnn dno doa dob dod dok don doo ka- kaa kab kad kak kan kao kba kbb kbd kbk kbn kbo kda kdb kdk kdo kkb kkk kkn kn- kna knd knk knn kno koa kob kod kok kon koo naa nab nad nak nan nao nba nbb nbd nbk nbn nbo nda ndb ndd ndk ndn ndo nka nkk nkn nko nna nnb nnk nnn nno no- noa nob nod nok non noo oaa oab oad oak oan oao ob- oba obb obd obk obn obo oda odb odd odn odo oka okb okd okk oko on- ona onb ond onk onn ono oo- ooa oob ood ook oon ooo