Graduate students should further allow users to erase a circle by clicking the right-button of a mouse
inside a drawn circle. So when there is a GLUT RIGHT BUTTON event, your code should perform a
linear retrieval of the array of the left-click points to test whether the right-click point is inside the circle
of a certain left-click points. If there is such a point, it should be removed from the array, then the rest
of elements should be moved forward to the hole. (A more efficient data structure is the list. If you
are familiar with C programming, you are encouraged to use list data structure to record the left-click
points.) Since it is possible that the drawn circles are overlapping and the right-click points are inside
multiple circles, your code should search through the entire array and remove all “relevant” left-click
points.