c-- ccc cce ccf cck ccn cco ce- cec cee cef cek cen ceo cfc cfe cff cfk cfn cfo ckc cko cn- cnc cne cnf cnn cno co- coc coe cof cok con coo ec- ecc ece ecf eck ecn eco eec eee eef eek een eeo ef- efc efe eff efo ekc eke ekf eko en- enc ene enf enk enn eno eo- eoc eoe eof eok eon eoo fcc fce fcf fck fcn fco fec fee fef fek fen feo ffc ffe fff ffk ffn ffo fkc fkf fkk fnc fne fnf fnk fnn foc foe fof fok fon foo kcc kce kck kcn ke- kec kee kef kek ken keo kfc kff kfo kkc kke kkk kkn kn- knc kne knf knk knn kno koc koe kof kok kon koo ncc nce ncf nck ncn nco ne- nec nee nef nek nen neo nfc nfe nff nfk nfn nfo nkc nke nkf nkk nkn nko nnc nne nnf nnk nnn nno no- noc noe nof nok non noo oc- occ ocf ock ocn oco oec oee oef oen oeo of- ofc ofe off ofn ofo okc oke okk oko on- onc one onf onk onn ono oo- ooc oof ook oon ooo