c-- ccc cck cco ccr ccs ckc cko cks cky co- coc cok coo cor cos coy crc crk cro crr crs cry csc csk cso csr css csy cyc cyk cyo cyr cys kcc kck kcr kcs kkc kkk kkr kks kky koc kok koo kor kos koy krc krk kro krr krs kry ksc ksk kso ksr kss kyc kyo kyr kys oc- occ ock oco ocr ocs okc okk oko okr oks oo- ooc ook ooo oor oos or- orc ork oro orr ors ory os- osc osk oso osr oss oyo oys rcc rco rcr rcs rkc rkk rko rks rky roc rok roo ror ros roy rrc rrk rrr rrs rsc rsk rso rsr rss ry- ryc ryk ryo ryr rys ryy scc sck sco scr scs sk- skc skk sko skr sks sky soc sok soo sor sos soy sr- src srk sro srr srs sry ss- ssc ssk sso ssr sss sy- syc syk syr sys ycc yco ycs ycy ykk yoc yok yoo yor yos yoy yrc yro yrs ysc ysk yso ysr yss ysy yyc yys yyy