c-- ccc ccf ccg cck cco ccr cfc cff cfg cfk cfo cfr cgc cgg cgo cgr ckc cko co- coc cof cog cok coo cor crc crf crg crk cro crr fcc fcf fcg fck fco fcr ffc fff ffg ffk ffo ffr fgc fgf fgg fgr fkc fkf fkg fkk foc fof fog fok foo for frc frf frg frk fro frr gcc gcf gcg gck gco gcr gfc gff gfk gfo gfr ggc ggg ggo ggr gko goc gof gog gok goo gor grc grf grg grk gro grr kcc kcg kck kcr kfc kff kfg kfo kgc kgf kgo kkc kkk kkr koc kof kog kok koo kor krc krf krg krk kro krr oc- occ ocf ocg ock oco ocr of- ofc off ofg ofo ofr ogc ogf ogg ogo okc okg okk oko okr oo- ooc oof oog ook ooo oor or- orc orf org ork oro orr rcc rcf rcg rco rcr rfc rff rfg rfk rfo rfr rgc rgf rgg rgk rgo rgr rkc rkf rkg rkk rko roc rof rog rok roo ror rrc rrf rrg rrk rrr