c-- ccc ccd cce ccf cck cdc cdd cde cdf cdk ce- cec ced cee cef cek cfc cfd cfe cff cfk ckc ckd dcc dcd dce dcf dck ddc ddd dde ddf ddk de- dec ded dee def dek dfc dfd dfe dff dfk dkc dke dkk ec- ecc ecd ece ecf eck ed- edc edd ede edf edk eec eed eee eef eek ef- efc efd efe eff ekc ekd eke ekf fcc fcd fce fcf fck fdc fdd fde fdf fdk fec fed fee fef fek ffc ffd ffe fff ffk fkc fkf fkk kcc kcd kce kck kdc kde kdf kdk ke- kec ked kee kef kek kfc kfd kff kkc kke kkk