-er c-- ccc ccd cce ccf cck cco ccr cdc cdd cde cdf cdk cdo cdr ce- cec ced cee cef cek ceo cer cfc cfd cfe cff cfk cfo cfr ckc ckd cko co- coc cod coe cof cok coo cor crc crd cre crf crk cro crr dcc dcd dce dcf dck dco dcr ddc ddd dde ddf ddk ddo ddr de- dec ded dee def dek deo der dfc dfd dfe dff dfk dfo dfr dkc dke dkk dko dkr doc dod doe dof dok doo dor drc drd dre drk dro drr ec- ecc ecd ece ecf eck eco ecr ed- edc edd ede edf edk edo edr eec eed eee eef eek eeo eer ef- efc efd efe eff efo efr ekc ekd eke ekf eko ekr eo- eoc eod eoe eof eok eoo eor erc erd ere erf erk ero err fcc fcd fce fcf fck fco fcr fdc fdd fde fdf fdk fdo fdr fec fed fee fef fek feo fer ffc ffd ffe fff ffk ffo ffr fkc fkf fkk foc foe fof fok foo for frc frd fre frf frk fro frr kcc kcd kce kck kcr kdc kde kdf kdk kdo kdr ke- kec ked kee kef kek keo ker kfc kfd kff kfo kkc kke kkk kkr koc kod koe kof kok koo kor krc krd krf krk kro krr oc- occ ocd ocf ock oco ocr odc odd ode odf odo odr oec oed oee oef oeo oer of- ofc ofd ofe off ofo ofr okc okd oke okk oko okr oo- ooc ood oof ook ooo oor or- orc ord ore orf ork oro orr rcc rcd rce rcf rco rcr rdc rdd rde rdf rdo rdr re- rec red ree ref rek reo rer rfc rfd rfe rff rfk rfo rfr rkc rke rkf rkk rko roc rod roe rof rok roo ror rrc rrd rrf rrk rrr