-er bbb bbd bbe bbr bbs bbt bdb bdd bde bdr bds bdt be- beb bed bee ber bes bet brb brd bre brr brs brt bsb bsd bse bsr bss bst btb btd bte btr bts btt dbb dbd dbe dbr dbs dbt ddb ddd dde ddr dds ddt de- deb ded dee der des det drb drd dre drr drs drt dsb dsd dse dsr dss dst dtb dtd dte dtr dts dtt ebb ebd ebe ebr ebs ebt ed- edb edd ede edr eds edt eeb eed eee eer ees eet erb erd ere err ers ert es- esb esd ese esr ess est etb etd ete etr ets ett rbb rbd rbe rbr rbs rbt rdb rdd rde rdr rds rdt re- reb red ree rer res ret rrb rrd rrr rrs rrt rsb rsd rse rsr rss rst rtb rtd rte rtr rts rtt sbb sbd sbe sbr sbs sbt sdb sdd sde sdr sds sdt se- seb sed see ser ses set sr- srb srd sre srr srs srt ss- ssb ssd sse ssr sss sst stb std ste str sts stt tbb tbd tbe tbr tbs tbt tdb tdd tde tdr tds tdt te- teb ted tee ter tes tet trb trd tre trr trs trt tsb tsd tse tsr tss tst ttb ttd tte ttr tts ttt