c-- ccc ccf cck ccn cco ccs cfc cff cfk cfn cfo cfs ckc cko cks cn- cnc cnf cnn cno cns co- coc cof cok con coo cos csc csf csk csn cso css fcc fcf fck fcn fco fcs ffc fff ffk ffn ffo ffs fkc fkf fkk fnc fnf fnk fnn fns foc fof fok fon foo fos fsc fsf fsk fsn fso fss kcc kck kcn kcs kfc kff kfo kfs kkc kkk kkn kks kn- knc knf knk knn kno koc kof kok kon koo kos ksc ksf ksk ksn kso kss ncc ncf nck ncn nco ncs nfc nff nfk nfn nfo nfs nkc nkf nkk nkn nko nks nnc nnf nnk nnn nno nns no- noc nof nok non noo nos nsc nsf nsk nsn nso nss oc- occ ocf ock ocn oco ocs of- ofc off ofn ofo ofs okc okk oko oks on- onc onf onk onn ono ons oo- ooc oof ook oon ooo oos os- osc osf osk osn oso oss scc scf sck scn sco scs sfc sff sfk sfn sfo sfs sk- skc skf skk sko sks snc snf snk snn sno sns soc sof sok son soo sos ss- ssc ssf ssk ssn sso sss