-er bbb bbd bbe bbo bbr bbt bdb bdd bde bdo bdr bdt be- beb bed bee beo ber bet bob bod boe boo bor bot brb brd bre bro brr brt btb btd bte bto btr btt dbb dbd dbe dbo dbr dbt ddb ddd dde ddo ddr ddt de- deb ded dee deo der det dob dod doe doo dor dot drb drd dre dro drr drt dtb dtd dte dto dtr dtt ebb ebd ebe ebo ebr ebt ed- edb edd ede edo edr edt eeb eed eee eeo eer eet eo- eob eod eoe eoo eor eot erb erd ere ero err ert etb etd ete eto etr ett ob- obb obd obe obo obr obt odb odd ode odo odr odt oeb oed oee oeo oer oet oo- oob ood ooo oor oot or- orb ord ore oro orr ort ot- otb otd ote oto otr ott rbb rbd rbe rbo rbr rbt rdb rdd rde rdo rdr rdt re- reb red ree reo rer ret rob rod roe roo ror rot rrb rrd rrr rrt rtb rtd rte rto rtr rtt tbb tbd tbe tbo tbr tbt tdb tdd tde tdo tdr tdt te- teb ted tee teo ter tet to- tob tod toe too tor tot trb trd tre tro trr trt ttb ttd tte tto ttr ttt