a-a a-b aaa aab aad aah aao ab- aba abb abd abh abo ad- ada adb add adh ado aha ahb ahd ahh aho aoa aob aod aoh aoo baa bab bad bah bao bba bbb bbd bbh bbo bda bdb bdd bdh bdo bha bhb bhd bhh bho boa bob bod boh boo daa dab dad dah dao dba dbb dbd dbh dbo dda ddb ddd ddh ddo dh- dha dhb dhd dhh dho doa dob dod doh doo haa hab had hah hao hba hbb hbd hbh hbo hda hdb hdd hdh hdo hha hhb hhd hhh hho hoa hob hod hoh hoo oaa oab oad oah oao ob- oba obb obd obh obo oda odb odd odh odo oha ohd ohh oho oo- ooa oob ood ooh ooo