a-a a-b aaa aab aao aau aay ab- aba abb abo abu aby aoa aob aoo aou au- aua aub auo ay- aya ayo ayu b-u baa bab bao bau bay bba bbb bbo bbu bby boa bob boo bou boy bua bub buo buu buy by- bya byo byu oaa oab oao oau ob- oba obb obo obu oby oo- ooa oob ooo ou- oua ouo oya oyo ua- uaa uab uao uau uay uba ubb ubo ubu uby uoa uob uoo uua uuu uyo uyu yaa yab yao yau yay yby yob yoo you yoy yua yuo yuu yuy yyb yyu yyy