c-- ccc ccf cck ccn cco cfc cff cfk cfn cfo ckc cko cn- cnc cnf cnn cno co- coc cof cok con coo fcc fcf fck fcn fco ffc fff ffk ffn ffo fkc fkf fkk fnc fnf fnk fnn foc fof fok fon foo kcc kck kcn kfc kff kfo kkc kkk kkn kn- knc knf knk knn kno koc kof kok kon koo ncc ncf nck ncn nco nfc nff nfk nfn nfo nkc nkf nkk nkn nko nnc nnf nnk nnn nno no- noc nof nok non noo oc- occ ocf ock ocn oco of- ofc off ofn ofo okc okk oko on- onc onf onk onn ono oo- ooc oof ook oon ooo