And then this is another subdivision. And when you do Riemann sums, you don't have to have equal subdivisions, although that's what you'll often see. So we've just divided going from one to 10 into three equal sections that are three wide. So that's three, this is three, and this is three. And so the question is, how do we define the height of these subdivisions which are going to end up being rectangles? And that's where the right Riemann sum applies. If we were doing a left Riemann sum, we would use the left boundary of each of the subdivisions and the value of the function there to define the height of the rectangle.