And then they say where the second derivative is less than zero. So this means that the slope itself, whether it's positive or negative, that it's actually decreasing. We are going to be concave downwards right over here. The slope itself, it could be positive, but it'll be coming less and less and less positive. And so we're looking for a place where the slope is positive, but it's becoming less and less and less positive. If you look right over here, the slope is positive, but the slope is increasing. It's getting steeper and steeper and steeper as we go.