-er bbb bbd bbe bbo bbr bdb bdd bde bdo bdr be- beb bed bee beo ber bob bod boe boo bor brb brd bre bro brr dbb dbd dbe dbo dbr ddb ddd dde ddo ddr de- deb ded dee deo der dob dod doe doo dor drb drd dre dro drr ebb ebd ebe ebo ebr ed- edb edd ede edo edr eeb eed eee eeo eer eo- eob eod eoe eoo eor erb erd ere ero err ob- obb obd obe obo obr odb odd ode odo odr oeb oed oee oeo oer oo- oob ood ooo oor or- orb ord ore oro orr rbb rbd rbe rbo rbr rdb rdd rde rdo rdr re- reb red ree reo rer rob rod roe roo ror rrb rrd rrr