c-- ccc cck cco ccr ccs cct ckc cko cks ckt co- coc cok coo cor cos cot crc crk cro crr crs crt csc csk cso csr css cst ctc ctk cto ctr cts ctt k-t kcc kck kcr kcs kct kkc kkk kkr kks kkt koc kok koo kor kos kot krc krk kro krr krs krt ksc ksk kso ksr kss kst ktc ktk kto ktr kts ktt oc- occ ock oco ocr ocs oct okc okk oko okr oks oo- ooc ook ooo oor oos oot or- orc ork oro orr ors ort os- osc osk oso osr oss ost ot- otc otk oto otr ots ott rcc rco rcr rcs rct rkc rkk rko rks rkt roc rok roo ror ros rot rrc rrk rrr rrs rrt rsc rsk rso rsr rss rst rtc rtk rto rtr rts rtt scc sck sco scr scs sct sk- skc skk sko skr sks skt soc sok soo sor sos sot sr- src srk sro srr srs srt ss- ssc ssk sso ssr sss sst stc stk sto str sts stt tcc tck tco tcr tcs tct tkc tkk tko tkr tks tkt to- toc tok too tor tos tot trc trk tro trr trs trt tsc tsk tso tsr tss tst ttc ttk tto ttr tts ttt