-er bbb bbc bbd bbe bbo bbr bbs bcb bcc bcd bce bco bcr bcs bdb bdc bdd bde bdo bdr bds be- beb bec bed bee beo ber bes bob boc bod boe boo bor bos brb brd bre bro brr brs bsb bsc bsd bse bso bsr bss c-- cbb cbc cbd cbe cbo cbr cbs ccb ccc ccd cce cco ccr ccs cdb cdc cdd cde cdo cdr cds ce- ceb cec ced cee ceo cer ces co- cob coc cod coe coo cor cos crb crc crd cre cro crr crs csb csc csd cse cso csr css dbb dbc dbd dbe dbo dbr dbs dcb dcc dcd dce dco dcr dcs ddb ddc ddd dde ddo ddr dds de- deb dec ded dee deo der des dob doc dod doe doo dor dos drb drc drd dre dro drr drs dsb dsc dsd dse dso dsr dss ebb ebc ebd ebe ebo ebr ebs ec- ecb ecc ecd ece eco ecr ecs ed- edb edc edd ede edo edr eds eeb eec eed eee eeo eer ees eo- eob eoc eod eoe eoo eor eos erb erc erd ere ero err ers es- esb esc esd ese eso esr ess ob- obb obc obd obe obo obr obs oc- ocb occ ocd oco ocr ocs odb odc odd ode odo odr ods oeb oec oed oee oeo oer oes oo- oob ooc ood ooo oor oos or- orb orc ord ore oro orr ors os- osb osc osd ose oso osr oss rbb rbc rbd rbe rbo rbr rbs rcb rcc rcd rce rco rcr rcs rdb rdc rdd rde rdo rdr rds re- reb rec red ree reo rer res rob roc rod roe roo ror ros rrb rrc rrd rrr rrs rsb rsc rsd rse rso rsr rss sbb sbc sbd sbe sbo sbr sbs scb scc scd sce sco scr scs sdb sdc sdd sde sdo sdr sds se- seb sec sed see seo ser ses sob soc sod soe soo sor sos sr- srb src srd sre sro srr srs ss- ssb ssc ssd sse sso ssr sss