Well, your profit as a function of x is just going to be equal to your revenue as a function of x minus your cost as a function of x. Minus your cost as a function of x. If you produce a certain amount, and let's say you bring in, I don't know, $10,000 of revenue and it costs you $5,000 to produce those shoes, you'll have $5,000 in profit. Those numbers aren't the ones that would actually, you would get from this right here. I'm just giving you an example. So this is what you want to optimize. You want to optimize p as a function, optimize p as a function of x.