So it's getting more and more and more negative until about that point. And now it looks like it's getting less and less and less and less negative, all the way until the derivative goes back to being zero. And then it looks like it's getting more and more and more and more positive. So the derivative of this magenta curve looks like an upward-opening U. And we don't see that over here. So we could feel good that its derivative actually isn't depicted. So I feel good calling the middle graph F, calling the left graph F prime, and calling the right graph the second derivative.