-er bbb bbd bbe bbo bbr bbs bbt bdb bdd bde bdo bdr bds bdt be- beb bed bee beo ber bes bet bob bod boe boo bor bos bot brb brd bre bro brr brs brt bsb bsd bse bso bsr bss bst btb btd bte bto btr bts btt dbb dbd dbe dbo dbr dbs dbt ddb ddd dde ddo ddr dds ddt de- deb ded dee deo der des det dob dod doe doo dor dos dot drb drd dre dro drr drs drt dsb dsd dse dso dsr dss dst dtb dtd dte dto dtr dts dtt ebb ebd ebe ebo ebr ebs ebt ed- edb edd ede edo edr eds edt eeb eed eee eeo eer ees eet eo- eob eod eoe eoo eor eos eot erb erd ere ero err ers ert es- esb esd ese eso esr ess est etb etd ete eto etr ets ett ob- obb obd obe obo obr obs obt odb odd ode odo odr ods odt oeb oed oee oeo oer oes oet oo- oob ood ooo oor oos oot or- orb ord ore oro orr ors ort os- osb osd ose oso osr oss ost ot- otb otd ote oto otr ots ott rbb rbd rbe rbo rbr rbs rbt rdb rdd rde rdo rdr rds rdt re- reb red ree reo rer res ret rob rod roe roo ror ros rot rrb rrd rrr rrs rrt rsb rsd rse rso rsr rss rst rtb rtd rte rto rtr rts rtt sbb sbd sbe sbo sbr sbs sbt sdb sdd sde sdo sdr sds sdt se- seb sed see seo ser ses set sob sod soe soo sor sos sot sr- srb srd sre sro srr srs srt ss- ssb ssd sse sso ssr sss sst stb std ste sto str sts stt tbb tbd tbe tbo tbr tbs tbt tdb tdd tde tdo tdr tds tdt te- teb ted tee teo ter tes tet to- tob tod toe too tor tos tot trb trd tre tro trr trs trt tsb tsd tse tso tsr tss tst ttb ttd tte tto ttr tts ttt