c-- ccc cck ccn cco ccr ckc cko cn- cnc cnn cno cnr co- coc cok con coo cor crc crk crn cro crr kcc kck kcn kcr kkc kkk kkn kkr kn- knc knk knn kno knr koc kok kon koo kor krc krk krn kro krr ncc nck ncn nco ncr nkc nkk nkn nko nkr nnc nnk nnn nno no- noc nok non noo nor nrc nrk nrn nro nrr oc- occ ock ocn oco ocr okc okk oko okr on- onc onk onn ono onr oo- ooc ook oon ooo oor or- orc ork orn oro orr rcc rcn rco rcr rkc rkk rko rnc rnn rno rnr roc rok ron roo ror rrc rrk rrn rrr