-er bbb bbd bbe bbo bbr bbx bdb bdd bde bdo bdr bdx be- beb bed bee beo ber bex bob bod boe boo bor box brb brd bre bro brr brx bxb bxd bxo bxx dbb dbd dbe dbo dbr dbx ddb ddd dde ddo ddr ddx de- deb ded dee deo der dex dob dod doe doo dor dox drb drd dre dro drr drx dxd dxo dxr dxx ebb ebd ebe ebo ebr ebx ed- edb edd ede edo edr edx eeb eed eee eeo eer eex eo- eob eod eoe eoo eor erb erd ere ero err ex- exd exe exo exr exx ob- obb obd obe obo obr obx odb odd ode odo odr oeb oed oee oeo oer oex oo- oob ood ooo oor oox or- orb ord ore oro orr orx ox- oxb oxo oxx rbb rbd rbe rbo rbr rbx rdb rdd rde rdo rdr rdx re- reb red ree reo rer rex rob rod roe roo ror rox rrb rrd rrr rxr xbe xbr xbx xdb xde xdr xed xee xer xex xod xoo xor xox xrd xrx xxo xxx