a-a a-b a-i aaa aab aai aao aay ab- aba abb abi abo aby ai- aia aib aii aio aiy aoa aob aoi aoo ay- aya ayi ayo baa bab bai bao bay bba bbb bbi bbo bby bi- bia bib bii bio biy boa bob boi boo boy by- bya byi byo ia- iaa iab iai iao iba ibb ibi ibo iby iia iib iii iio io- ioa iob ioi ioo iya iyo iyy o-i oaa oab oai oao ob- oba obb obi obo oby oia oib oii oio oo- ooa oob ooi ooo oya oyi oyo yaa yab yai yao yay ybi yby yii yio yob yoi yoo yoy yyb yyy