c-- ccc ccd cck ccn cco cdc cdd cdk cdn cdo ckc ckd cko cn- cnc cnd cnn cno co- coc cod cok con coo dcc dcd dck dcn dco ddc ddd ddk ddn ddo dkc dkk dko dnc dnd dnk dnn dno doc dod dok don doo kcc kcd kck kcn kdc kdk kdo kkc kkk kkn kn- knc knd knk knn kno koc kod kok kon koo ncc ncd nck ncn nco ndc ndd ndk ndn ndo nkc nkk nkn nko nnc nnk nnn nno no- noc nod nok non noo oc- occ ocd ock ocn oco odc odd odn odo okc okd okk oko on- onc ond onk onn ono oo- ooc ood ook oon ooo