-er c-- ccc cce cck cco ccr cct ce- cec cee cek ceo cer cet ckc cko ckt co- coc coe cok coo cor cot crc cre crk cro crr crt ctc cte ctk cto ctr ctt ec- ecc ece eck eco ecr ect eec eee eek eeo eer eet ekc eke eko ekr ekt eo- eoc eoe eok eoo eor eot erc ere erk ero err ert etc ete etk eto etr ett k-t kcc kce kck kcr kct ke- kec kee kek keo ker ket kkc kke kkk kkr kkt koc koe kok koo kor kot krc krk kro krr krt ktc kte ktk kto ktr ktt oc- occ ock oco ocr oct oec oee oeo oer oet okc oke okk oko okr oo- ooc ook ooo oor oot or- orc ore ork oro orr ort ot- otc ote otk oto otr ott rcc rce rco rcr rct re- rec ree rek reo rer ret rkc rke rkk rko rkt roc roe rok roo ror rot rrc rrk rrr rrt rtc rte rtk rto rtr rtt tcc tce tck tco tcr tct te- tec tee tek teo ter tet tkc tke tkk tko tkr tkt to- toc toe tok too tor tot trc tre trk tro trr trt ttc tte ttk tto ttr ttt