c-- ccc ccf cck cco ccr ccu cfc cff cfk cfo cfr cfu ckc cko co- coc cof cok coo cor cou crc crf crk cro crr cru cuc cuf cuk cuo cur cuu fcc fcf fck fco fcr fcu ffc fff ffk ffo ffr ffu fkc fkf fkk foc fof fok foo for fou frc frf frk fro frr fru fuf fuk fuo fur fuu kcc kck kcr kcu kfc kff kfo kfu kkc kkk kkr kku koc kof kok koo kor kou krc krf krk kro krr kru kuc kuk kur kuu oc- occ ocf ock oco ocr ocu of- ofc off ofo ofr ofu okc okk oko okr oku oo- ooc oof ook ooo oor or- orc orf ork oro orr oru ou- ouc ouf ouk ouo our rcc rcf rco rcr rcu rfc rff rfk rfo rfr rfu rkc rkf rkk rko rku roc rof rok roo ror rou rrc rrf rrk rrr rru ruc ruf ruk ruo rur ruu ucc ucf uck uco ucr ucu ufc uff ufo ufr ufu ukc ukf ukk ukr uku uoc uok uoo uor ur- urc urf urk uro urr uru uuc uur uuu