-er a-a a-b aaa aab aad aae aao aar ab- aba abb abd abe abo abr ad- ada adb add ade ado adr aea aeb aed aee aeo aer aoa aob aod aoe aoo aor ar- ara arb ard are aro arr baa bab bad bae bao bar bba bbb bbd bbe bbo bbr bda bdb bdd bde bdo bdr be- bea beb bed bee beo ber boa bob bod boe boo bor bra brb brd bre bro brr daa dab dad dae dao dar dba dbb dbd dbe dbo dbr dda ddb ddd dde ddo ddr de- dea deb ded dee deo der doa dob dod doe doo dor dra drb drd dre dro drr eaa eab ead eae eao ear eba ebb ebd ebe ebo ebr ed- eda edb edd ede edo edr eea eeb eed eee eeo eer eo- eoa eob eod eoe eoo eor era erb erd ere ero err oaa oab oad oae oao oar ob- oba obb obd obe obo obr oda odb odd ode odo odr oea oeb oed oee oeo oer oo- ooa oob ood ooo oor or- ora orb ord ore oro orr ra- raa rab rad rae rao rar rba rbb rbd rbe rbo rbr rda rdb rdd rde rdo rdr re- rea reb red ree reo rer roa rob rod roe roo ror rra rrb rrd rrr