-er bbb bbd bbe bbo bbr bbs bdb bdd bde bdo bdr bds be- beb bed bee beo ber bes bob bod boe boo bor bos brb brd bre bro brr brs bsb bsd bse bso bsr bss dbb dbd dbe dbo dbr dbs ddb ddd dde ddo ddr dds de- deb ded dee deo der des dob dod doe doo dor dos drb drd dre dro drr drs dsb dsd dse dso dsr dss ebb ebd ebe ebo ebr ebs ed- edb edd ede edo edr eds eeb eed eee eeo eer ees eo- eob eod eoe eoo eor eos erb erd ere ero err ers es- esb esd ese eso esr ess ob- obb obd obe obo obr obs odb odd ode odo odr ods oeb oed oee oeo oer oes oo- oob ood ooo oor oos or- orb ord ore oro orr ors os- osb osd ose oso osr oss rbb rbd rbe rbo rbr rbs rdb rdd rde rdo rdr rds re- reb red ree reo rer res rob rod roe roo ror ros rrb rrd rrr rrs rsb rsd rse rso rsr rss sbb sbd sbe sbo sbr sbs sdb sdd sde sdo sdr sds se- seb sed see seo ser ses sob sod soe soo sor sos sr- srb srd sre sro srr srs ss- ssb ssd sse sso ssr sss