-er bbb bbc bbd bbe bbf bbk bbo bbr bcb bcc bcd bce bcf bck bco bcr bdb bdc bdd bde bdf bdk bdo bdr be- beb bec bed bee bef bek beo ber bfb bfc bfd bfe bff bfo bfr bkb bkc bke bkf bkk bko bkr bob boc bod boe bof bok boo bor brb brd bre brf brk bro brr c-- cbb cbc cbd cbe cbf cbk cbo cbr ccb ccc ccd cce ccf cck cco ccr cdb cdc cdd cde cdf cdk cdo cdr ce- ceb cec ced cee cef cek ceo cer cfb cfc cfd cfe cff cfk cfo cfr ckb ckc ckd cko co- cob coc cod coe cof cok coo cor crb crc crd cre crf crk cro crr dbb dbc dbd dbe dbf dbk dbo dbr dcb dcc dcd dce dcf dck dco dcr ddb ddc ddd dde ddf ddk ddo ddr de- deb dec ded dee def dek deo der dfb dfc dfd dfe dff dfk dfo dfr dkb dkc dke dkk dko dkr dob doc dod doe dof dok doo dor drb drc drd dre drk dro drr ebb ebc ebd ebe ebf ebk ebo ebr ec- ecb ecc ecd ece ecf eck eco ecr ed- edb edc edd ede edf edk edo edr eeb eec eed eee eef eek eeo eer ef- efb efc efd efe eff efo efr ekb ekc ekd eke ekf eko ekr eo- eob eoc eod eoe eof eok eoo eor erb erc erd ere erf erk ero err fbb fbc fbd fbe fbf fbk fbo fbr fcb fcc fcd fce fcf fck fco fcr fdb fdc fdd fde fdf fdk fdo fdr feb fec fed fee fef fek feo fer ffc ffd ffe fff ffk ffo ffr fkb fkc fkf fkk fob foc foe fof fok foo for frb frc frd fre frf frk fro frr kbb kbc kbd kbe kbf kbk kbo kbr kcb kcc kcd kce kck kcr kdb kdc kde kdf kdk kdo kdr ke- keb kec ked kee kef kek keo ker kfc kfd kff kfo kkb kkc kke kkk kkr kob koc kod koe kof kok koo kor krc krd krf krk kro krr ob- obb obc obd obe obf obk obo obr oc- ocb occ ocd ocf ock oco ocr odb odc odd ode odf odo odr oeb oec oed oee oef oeo oer of- ofb ofc ofd ofe off ofo ofr okb okc okd oke okk oko okr oo- oob ooc ood oof ook ooo oor or- orb orc ord ore orf ork oro orr rbb rbc rbd rbe rbf rbk rbo rbr rcb rcc rcd rce rcf rco rcr rdb rdc rdd rde rdf rdo rdr re- reb rec red ree ref rek reo rer rfb rfc rfd rfe rff rfk rfo rfr rkb rkc rke rkf rkk rko rob roc rod roe rof rok roo ror rrb rrc rrd rrf rrk rrr