a-a a-b aaa aab aad aae aao ab- aba abb abd abe abo ad- ada adb add ade ado aea aeb aed aee aeo aoa aob aod aoe aoo baa bab bad bae bao bba bbb bbd bbe bbo bda bdb bdd bde bdo be- bea beb bed bee beo boa bob bod boe boo daa dab dad dae dao dba dbb dbd dbe dbo dda ddb ddd dde ddo de- dea deb ded dee deo doa dob dod doe doo eaa eab ead eae eao eba ebb ebd ebe ebo ed- eda edb edd ede edo eea eeb eed eee eeo eo- eoa eob eod eoe eoo oaa oab oad oae oao ob- oba obb obd obe obo oda odb odd ode odo oea oeb oed oee oeo oo- ooa oob ood ooo