a-a a-b aaa aab aad aao aaw ab- aba abb abd abo abw ad- ada adb add ado adw aoa aob aod aoo aow aw- awa awb awd awo aww baa bab bad bao baw bba bbb bbd bbo bbw bda bdb bdd bdo bdw boa bob bod boo bow bwa bwb bwd bwo daa dab dad dao daw dba dbb dbd dbo dda ddb ddd ddo ddw doa dob dod doo dow dwa dwb dwo dww oaa oab oad oao oaw ob- oba obb obd obo obw oda odb odd odo oo- ooa oob ood ooo oow owa owb owd owo oww waa wab wad wao waw wba wbb wbd wbo wbw wda wdb woa wob wod woo wow wwa wwd wwo www