c-- ccc cco ccr ccs cct co- coc coo cor cos cot crc cro crr crs crt csc cso csr css cst ctc cto ctr cts ctt oc- occ oco ocr ocs oct oo- ooc ooo oor oos oot or- orc oro orr ors ort os- osc oso osr oss ost ot- otc oto otr ots ott rcc rco rcr rcs rct roc roo ror ros rot rrc rrr rrs rrt rsc rso rsr rss rst rtc rto rtr rts rtt scc sco scr scs sct soc soo sor sos sot sr- src sro srr srs srt ss- ssc sso ssr sss sst stc sto str sts stt tcc tco tcr tcs tct to- toc too tor tos tot trc tro trr trs trt tsc tso tsr tss tst ttc tto ttr tts ttt