c-- ccc ccd ccf ccn cco cdc cdd cdf cdn cdo cfc cfd cff cfn cfo cn- cnc cnd cnf cnn cno co- coc cod cof con coo dcc dcd dcf dcn dco ddc ddd ddf ddn ddo dfc dfd dff dfn dfo dnc dnd dnf dnn dno doc dod dof don doo fcc fcd fcf fcn fco fdc fdd fdf fdn fdo ffc ffd fff ffn ffo fnc fnd fnf fnn foc fof fon foo ncc ncd ncf ncn nco ndc ndd ndf ndn ndo nfc nfd nff nfn nfo nnc nnf nnn nno no- noc nod nof non noo oc- occ ocd ocf ocn oco odc odd odf odn odo of- ofc ofd off ofn ofo on- onc ond onf onn ono oo- ooc ood oof oon ooo