-er c-- ccc ccd cce cck cco ccr ccs cdc cdd cde cdk cdo cdr cds ce- cec ced cee cek ceo cer ces ckc ckd cko cks co- coc cod coe cok coo cor cos crc crd cre crk cro crr crs csc csd cse csk cso csr css dcc dcd dce dck dco dcr dcs ddc ddd dde ddk ddo ddr dds de- dec ded dee dek deo der des dkc dke dkk dko dkr dks doc dod doe dok doo dor dos drc drd dre drk dro drr drs dsc dsd dse dsk dso dsr dss ec- ecc ecd ece eck eco ecr ecs ed- edc edd ede edk edo edr eds eec eed eee eek eeo eer ees ekc ekd eke eko ekr eks eo- eoc eod eoe eok eoo eor eos erc erd ere erk ero err ers es- esc esd ese esk eso esr ess kcc kcd kce kck kcr kcs kdc kde kdk kdo kdr kds ke- kec ked kee kek keo ker kes kkc kke kkk kkr kks koc kod koe kok koo kor kos krc krd krk kro krr krs ksc ksd kse ksk kso ksr kss oc- occ ocd ock oco ocr ocs odc odd ode odo odr ods oec oed oee oeo oer oes okc okd oke okk oko okr oks oo- ooc ood ook ooo oor oos or- orc ord ore ork oro orr ors os- osc osd ose osk oso osr oss rcc rcd rce rco rcr rcs rdc rdd rde rdo rdr rds re- rec red ree rek reo rer res rkc rke rkk rko rks roc rod roe rok roo ror ros rrc rrd rrk rrr rrs rsc rsd rse rsk rso rsr rss scc scd sce sck sco scr scs sdc sdd sde sdk sdo sdr sds se- sec sed see sek seo ser ses sk- skc skd ske skk sko skr sks soc sod soe sok soo sor sos sr- src srd sre srk sro srr srs ss- ssc ssd sse ssk sso ssr sss