c-- ccc ccd cce ccf cco cdc cdd cde cdf cdo ce- cec ced cee cef ceo cfc cfd cfe cff cfo co- coc cod coe cof coo dcc dcd dce dcf dco ddc ddd dde ddf ddo de- dec ded dee def deo dfc dfd dfe dff dfo doc dod doe dof doo ec- ecc ecd ece ecf eco ed- edc edd ede edf edo eec eed eee eef eeo ef- efc efd efe eff efo eo- eoc eod eoe eof eoo fcc fcd fce fcf fco fdc fdd fde fdf fdo fec fed fee fef feo ffc ffd ffe fff ffo foc foe fof foo oc- occ ocd ocf oco odc odd ode odf odo oec oed oee oef oeo of- ofc ofd ofe off ofo oo- ooc ood oof ooo