So when we are less than four, our second derivative, g prime, the second derivative is greater than zero. So we are actually going to be concave upwards over this interval to the left of four. Now let's think about to the right of four. Two is a different color. So what about to the right of four? And so let me just evaluate, what would be an easy thing to evaluate? Well, I could evaluate g prime of, well, why not do g, or the second derivative, g prime prime, I should say, of 10.