-er bbb bbc bbd bbe bbo bbr bbt bcb bcc bcd bce bco bcr bct bdb bdc bdd bde bdo bdr bdt be- beb bec bed bee beo ber bet bob boc bod boe boo bor bot brb brd bre bro brr brt btb btc btd bte bto btr btt c-- cbb cbc cbd cbe cbo cbr cbt ccb ccc ccd cce cco ccr cct cdb cdc cdd cde cdo cdr cdt ce- ceb cec ced cee ceo cer cet co- cob coc cod coe coo cor cot crb crc crd cre cro crr crt ctb ctc ctd cte cto ctr ctt dbb dbc dbd dbe dbo dbr dbt dcb dcc dcd dce dco dcr dct ddb ddc ddd dde ddo ddr ddt de- deb dec ded dee deo der det dob doc dod doe doo dor dot drb drc drd dre dro drr drt dtb dtc dtd dte dto dtr dtt ebb ebc ebd ebe ebo ebr ebt ec- ecb ecc ecd ece eco ecr ect ed- edb edc edd ede edo edr edt eeb eec eed eee eeo eer eet eo- eob eoc eod eoe eoo eor eot erb erc erd ere ero err ert etb etc etd ete eto etr ett ob- obb obc obd obe obo obr obt oc- ocb occ ocd oco ocr oct odb odc odd ode odo odr odt oeb oec oed oee oeo oer oet oo- oob ooc ood ooo oor oot or- orb orc ord ore oro orr ort ot- otb otc otd ote oto otr ott rbb rbc rbd rbe rbo rbr rbt rcb rcc rcd rce rco rcr rct rdb rdc rdd rde rdo rdr rdt re- reb rec red ree reo rer ret rob roc rod roe roo ror rot rrb rrc rrd rrr rrt rtb rtc rtd rte rto rtr rtt tbb tbc tbd tbe tbo tbr tbt tcb tcc tcd tce tco tcr tct tdb tdc tdd tde tdo tdr tdt te- teb tec ted tee teo ter tet to- tob toc tod toe too tor tot trb trc trd tre tro trr trt ttb ttc ttd tte tto ttr ttt