c-- ccc cck cco ccs ckc cko cks cky co- coc cok coo cos coy csc csk cso css csy cyc cyk cyo cys kcc kck kcs kkc kkk kks kky koc kok koo kos koy ksc ksk kso kss kyc kyo kys oc- occ ock oco ocs okc okk oko oks oo- ooc ook ooo oos os- osc osk oso oss oyo oys scc sck sco scs sk- skc skk sko sks sky soc sok soo sos soy ss- ssc ssk sso sss sy- syc syk sys ycc yco ycs ycy ykk yoc yok yoo yos yoy ysc ysk yso yss ysy yyc yys yyy