And so I would say that this is f, then this is the derivative of that, which would make it f prime. And then we already established that this right graph is the derivative of the left one. So if it's the derivative of f prime, it's not f prime itself, it's the second derivative. So I feel pretty good about that. And just for good measure, we could think about what the derivative of this graph would look like. Here the slope is slightly negative, but then it gets more and more and more and more and more negative. So the derivative would have a similar shape here.