-er c-- ccc cce cck cco ccr ccs cct ce- cec cee cek ceo cer ces cet ckc cko cks ckt co- coc coe cok coo cor cos cot crc cre crk cro crr crs crt csc cse csk cso csr css cst ctc cte ctk cto ctr cts ctt ec- ecc ece eck eco ecr ecs ect eec eee eek eeo eer ees eet ekc eke eko ekr eks ekt eo- eoc eoe eok eoo eor eos eot erc ere erk ero err ers ert es- esc ese esk eso esr ess est etc ete etk eto etr ets ett k-t kcc kce kck kcr kcs kct ke- kec kee kek keo ker kes ket kkc kke kkk kkr kks kkt koc koe kok koo kor kos kot krc krk kro krr krs krt ksc kse ksk kso ksr kss kst ktc kte ktk kto ktr kts ktt oc- occ ock oco ocr ocs oct oec oee oeo oer oes oet okc oke okk oko okr oks oo- ooc ook ooo oor oos oot or- orc ore ork oro orr ors ort os- osc ose osk oso osr oss ost ot- otc ote otk oto otr ots ott rcc rce rco rcr rcs rct re- rec ree rek reo rer res ret rkc rke rkk rko rks rkt roc roe rok roo ror ros rot rrc rrk rrr rrs rrt rsc rse rsk rso rsr rss rst rtc rte rtk rto rtr rts rtt scc sce sck sco scr scs sct se- sec see sek seo ser ses set sk- skc ske skk sko skr sks skt soc soe sok soo sor sos sot sr- src sre srk sro srr srs srt ss- ssc sse ssk sso ssr sss sst stc ste stk sto str sts stt tcc tce tck tco tcr tcs tct te- tec tee tek teo ter tes tet tkc tke tkk tko tkr tks tkt to- toc toe tok too tor tos tot trc tre trk tro trr trs trt tsc tse tsk tso tsr tss tst ttc tte ttk tto ttr tts ttt