Suppose we have an image of a human face consisting of n x n pixels. In our simplified setting, a face consists of two eyes, two ears, one nose, and one mouth, each represented as an arbitrary axis-aligned rectangle (i.e. the axes of the rectangle are aligned with the axes of the image). As we'd like to handle Picasso portraits too, there are no constraints on the location or size of the rectangles. How many possible faces (choice of its component rectangles) are there? In general, we only care about asymptotic complexity, so give your answer in the form of O(n) or (c") for some integer c