一种画椭圆的工具如图1所示．$O$是滑槽$AB$的中点，短杆ON可绕O转动，长杆MN通过N处铰链与ON连接，MN上的栓子D可沿滑槽AB滑动，且$DN=ON=1$，$MN=3$．当栓子D在滑槽AB内作往复运动时，带动N绕O转动，M处的笔尖画出的椭圆记为C．以O为原点，AB所在的直线为$x$轴建立如图2所示的平面直角坐标系．

If someone spends his or her time, effort and money writing a book, for example, he or she deserves _______ for it.