a-a a-b aaa aab aak aan aao aay ab- aba abb abk abn abo aby aka akb akk akn ako an- ana anb ank ann ano any aoa aob aok aon aoo ay- aya ayk ayn ayo baa bab bak ban bao bay bba bbb bbk bbn bbo bby bka bkb bkk bkn bko bna bnb bnk bnn bno boa bob bok bon boo boy by- bya byk byn byo ka- kaa kab kak kan kao kay kba kbb kbk kbn kbo kkb kkk kkn kky kn- kna knk knn kno koa kob kok kon koo koy kya kyn kyo naa nab nak nan nao nay nba nbb nbk nbn nbo nka nkk nkn nko nky nna nnb nnk nnn nno no- noa nob nok non noo noy nya nyk nyn nyo nyy oaa oab oak oan oao ob- oba obb obk obn obo oby oka okb okk oko on- ona onb onk onn ono ony oo- ooa oob ook oon ooo oya oyo yaa yab yak yan yao yay yby yka ykk ykn yna ynk ynn yny yob yok yon yoo yoy yyb yyy