a-a a-b aaa aab aad aao aay ab- aba abb abd abo aby ad- ada adb add ado ady aoa aob aod aoo ay- aya ayd ayo baa bab bad bao bay bba bbb bbd bbo bby bda bdb bdd bdo bdy boa bob bod boo boy by- bya byd byo daa dab dad dao day dba dbb dbd dbo dby dda ddb ddd ddo ddy doa dob dod doo doy dy- dya dyb dyd dyo dyy oaa oab oad oao ob- oba obb obd obo oby oda odb odd odo oo- ooa oob ood ooo oya oyd oyo yaa yab yad yao yay yby yda ydo ydy yob yod yoo yoy yyb yyy