a-a a-b aaa aab aan aao aay ab- aba abb abn abo aby an- ana anb ann ano any aoa aob aon aoo ay- aya ayn ayo baa bab ban bao bay bba bbb bbn bbo bby bna bnb bnn bno boa bob bon boo boy by- bya byn byo naa nab nan nao nay nba nbb nbn nbo nna nnb nnn nno no- noa nob non noo noy nya nyn nyo nyy oaa oab oan oao ob- oba obb obn obo oby on- ona onb onn ono ony oo- ooa oob oon ooo oya oyo yaa yab yan yao yay yby yna ynn yny yob yon yoo yoy yyb yyy