Well, rectangle number 3, the left boundary, we're just going to call it x sub 2. And its height is going to be f of x sub 2. And its width is going to be the same width as the other ones. I'm just eyeballing it right over here. So this is rectangle number 3. And we're going to continue this process all the way until we get to rectangle number n. So this is the nth rectangle. The nth rectangle right over here.