c-- ccc cck ccn cco ccr ccs ckc cko cks cn- cnc cnn cno cnr cns co- coc cok con coo cor cos crc crk crn cro crr crs csc csk csn cso csr css kcc kck kcn kcr kcs kkc kkk kkn kkr kks kn- knc knk knn kno knr koc kok kon koo kor kos krc krk krn kro krr krs ksc ksk ksn kso ksr kss ncc nck ncn nco ncr ncs nkc nkk nkn nko nkr nks nnc nnk nnn nno nns no- noc nok non noo nor nos nrc nrk nrn nro nrr nrs nsc nsk nsn nso nsr nss oc- occ ock ocn oco ocr ocs okc okk oko okr oks on- onc onk onn ono onr ons oo- ooc ook oon ooo oor oos or- orc ork orn oro orr ors os- osc osk osn oso osr oss rcc rcn rco rcr rcs rkc rkk rko rks rnc rnn rno rnr rns roc rok ron roo ror ros rrc rrk rrn rrr rrs rsc rsk rsn rso rsr rss scc sck scn sco scr scs sk- skc skk sko skr sks snc snk snn sno snr sns soc sok son soo sor sos sr- src srk srn sro srr srs ss- ssc ssk ssn sso ssr sss