c-- ccc cck ccr ccs cct ckc cks ckt crc crk crr crs crt csc csk csr css cst ctc ctk ctr cts ctt k-t kcc kck kcr kcs kct kkc kkk kkr kks kkt krc krk krr krs krt ksc ksk ksr kss kst ktc ktk ktr kts ktt rcc rcr rcs rct rkc rkk rks rkt rrc rrk rrr rrs rrt rsc rsk rsr rss rst rtc rtk rtr rts rtt scc sck scr scs sct sk- skc skk skr sks skt sr- src srk srr srs srt ss- ssc ssk ssr sss sst stc stk str sts stt tcc tck tcr tcs tct tkc tkk tkr tks tkt trc trk trr trs trt tsc tsk tsr tss tst ttc ttk ttr tts ttt