c-- ccc ccf ccn cco ccs cfc cff cfn cfo cfs cn- cnc cnf cnn cno cns co- coc cof con coo cos csc csf csn cso css fcc fcf fcn fco fcs ffc fff ffn ffo ffs fnc fnf fnn fns foc fof fon foo fos fsc fsf fsn fso fss ncc ncf ncn nco ncs nfc nff nfn nfo nfs nnc nnf nnn nno nns no- noc nof non noo nos nsc nsf nsn nso nss oc- occ ocf ocn oco ocs of- ofc off ofn ofo ofs on- onc onf onn ono ons oo- ooc oof oon ooo oos os- osc osf osn oso oss scc scf scn sco scs sfc sff sfn sfo sfs snc snf snn sno sns soc sof son soo sos ss- ssc ssf ssn sso sss