But it is definitely positive. So it's positive going into that point, and then it becomes negative after we cross that point. The slope was undefined right at the point, but it did switch signs from positive to negative as we crossed that critical point. So these both meet our criteria for being a maximum point. So, so far, our criteria seems pretty good. Now let's make sure that somehow this point right over here, which we identified in the last video as a critical point, let's make, and I think we call this, let's see, this was x zero, this was x one, this was x two, this was x one, this was x two, so this is x three. Let's make sure that this doesn't somehow meet the criteria because we see visually that this is not a maximum point.