-er c-- ccc cce cck cco ccr cct ccv ce- cec cee cek ceo cer cet cev ckc cko ckt co- coc coe cok coo cor cot cov crc cre crk cro crr crt crv ctc cte ctk cto ctr ctt ctv cvc cve cvk cvo cvr cvt cvv ec- ecc ece eck eco ecr ect ecv eec eee eek eeo eer eet eev ekc eke eko ekr ekt ekv eo- eoc eoe eok eoo eor eot erc ere erk ero err ert erv etc ete etk eto etr ett etv evc eve evo evr evt evv k-t kcc kce kck kcr kct ke- kec kee kek keo ker ket kev kkc kke kkk kkr kkt kkv koc koe kok koo kor kot krc krk kro krr krt krv ktc kte ktk kto ktr ktt ktv kvk kvo kvr kvv oc- occ ock oco ocr oct ocv oec oee oeo oer oet okc oke okk oko okr oo- ooc ook ooo oor oot oov or- orc ore ork oro orr ort orv ot- otc ote otk oto otr ott otv ov- ovc ove ovo ovv rcc rce rco rcr rct rcv re- rec ree rek reo rer ret rev rkc rke rkk rko rkt rkv roc roe rok roo ror rot rov rrc rrk rrr rrt rtc rte rtk rto rtr rtt rtv rvc rve rvo rvr rvt rvv tcc tce tck tco tcr tct tcv te- tec tee tek teo ter tet tev tkc tke tkk tko tkr tkt to- toc toe tok too tor tot tov trc tre trk tro trr trt trv ttc tte ttk tto ttr ttt ttv tvc tve tvk tvo tvr tvt v-e vcc vce vco vcr vct vec vee vek veo ver vet vkt voc voe vok voo vor vot vov vrc vre vrk vrr vrt vtc vte vtk vto vtr vtt vtv vvc vvo vvr vvt vvv