It's either decreasing or staying flat. So if you use the value of the function at the right edge, it's going to be smaller, it's never going to be larger than the value that the function takes on in the rest of that subdivision. And so we are continuously underestimating. We're missing all of this area right over there is not being included, so we have an underestimate. So if we want to rank these from least to greatest, well, the right Riemann sum is the least. It is underestimating it. Then you have the actual area of the curve, which is just the area of the curve.