c-- ccc cck cco ccr cct ckc cko ckt co- coc cok coo cor cot crc crk cro crr crt ctc ctk cto ctr ctt k-t kcc kck kcr kct kkc kkk kkr kkt koc kok koo kor kot krc krk kro krr krt ktc ktk kto ktr ktt oc- occ ock oco ocr oct okc okk oko okr oo- ooc ook ooo oor oot or- orc ork oro orr ort ot- otc otk oto otr ott rcc rco rcr rct rkc rkk rko rkt roc rok roo ror rot rrc rrk rrr rrt rtc rtk rto rtr rtt tcc tck tco tcr tct tkc tkk tko tkr tkt to- toc tok too tor tot trc trk tro trr trt ttc ttk tto ttr ttt