a-a a-b aaa aab aad aak aan ab- aba abb abd abk abn ad- ada adb add adk adn aka akb akd akk akn an- ana anb and ank ann baa bab bad bak ban bba bbb bbd bbk bbn bda bdb bdd bdk bka bkb bkk bkn bna bnb bnd bnk bnn daa dab dad dak dan dba dbb dbd dbk dbn dda ddb ddd ddk ddn dka dkb dkk dna dnb dnd dnk dnn ka- kaa kab kad kak kan kba kbb kbd kbk kbn kda kdb kdk kkb kkk kkn kn- kna knd knk knn naa nab nad nak nan nba nbb nbd nbk nbn nda ndb ndd ndk ndn nka nkk nkn nna nnb nnk nnn