c-- ccc cck cco ccr ccu ckc cko co- coc cok coo cor cou crc crk cro crr cru cuc cuk cuo cur cuu kcc kck kcr kcu kkc kkk kkr kku koc kok koo kor kou krc krk kro krr kru kuc kuk kur kuu oc- occ ock oco ocr ocu okc okk oko okr oku oo- ooc ook ooo oor or- orc ork oro orr oru ou- ouc ouk ouo our rcc rco rcr rcu rkc rkk rko rku roc rok roo ror rou rrc rrk rrr rru ruc ruk ruo rur ruu ucc uck uco ucr ucu ukc ukk ukr uku uoc uok uoo uor ur- urc urk uro urr uru uuc uur uuu