-er c-- ccc ccd cce ccg cck cco ccr cdc cdd cde cdg cdk cdo cdr ce- cec ced cee ceg cek ceo cer cgc cgd cge cgg cgo cgr ckc ckd cko co- coc cod coe cog cok coo cor crc crd cre crg crk cro crr dcc dcd dce dcg dck dco dcr ddc ddd dde ddg ddk ddo ddr de- dec ded dee deg dek deo der dgc dgd dge dgg dgk dgr dkc dke dkg dkk dko dkr doc dod doe dog dok doo dor drc drd dre drg drk dro drr ec- ecc ecd ece ecg eck eco ecr ed- edc edd ede edg edk edo edr eec eed eee eeg eek eeo eer egc egd ege egg ego egr ekc ekd eke ekg eko ekr eo- eoc eod eoe eog eok eoo eor erc erd ere erg erk ero err g-d gcc gcd gce gcg gck gco gcr gdc gdd gde gdk gdo gdr ge- gec ged gee geg gek geo ger ggc ggd ggg ggo ggr gkd gko goc god goe gog gok goo gor grc grd gre grg grk gro grr kcc kcd kce kcg kck kcr kdc kde kdg kdk kdo kdr ke- kec ked kee keg kek keo ker kgc kgd kgo kkc kke kkk kkr koc kod koe kog kok koo kor krc krd krg krk kro krr oc- occ ocd ocg ock oco ocr odc odd ode odg odo odr oec oed oee oeg oeo oer ogc ogd oge ogg ogo okc okd oke okg okk oko okr oo- ooc ood oog ook ooo oor or- orc ord ore org ork oro orr rcc rcd rce rcg rco rcr rdc rdd rde rdg rdo rdr re- rec red ree reg rek reo rer rgc rgd rge rgg rgk rgo rgr rkc rke rkg rkk rko roc rod roe rog rok roo ror rrc rrd rrg rrk rrr