c-- ccc cce ccf cck cco ce- cec cee cef cek ceo cfc cfe cff cfk cfo ckc cko co- coc coe cof cok coo ec- ecc ece ecf eck eco eec eee eef eek eeo ef- efc efe eff efo ekc eke ekf eko eo- eoc eoe eof eok eoo fcc fce fcf fck fco fec fee fef fek feo ffc ffe fff ffk ffo fkc fkf fkk foc foe fof fok foo kcc kce kck ke- kec kee kef kek keo kfc kff kfo kkc kke kkk koc koe kof kok koo oc- occ ocf ock oco oec oee oef oeo of- ofc ofe off ofo okc oke okk oko oo- ooc oof ook ooo