Because from negative one to zero, I would think about x plus one, but then from zero to one, I would think about cosine pi x. And if you were thinking that, you're thinking in the right direction. And the way that we can make this a little bit more straightforward is to actually split up this definite integral. This is going to be equal to the definite integral from negative one to zero of f of x dx plus the integral from zero to one of f of x dx. Now, why was it useful for me to split it up this way? And in particular, to split it up, split the interval from negative one to one, split it into two intervals from negative one to zero and zero to one? Well, I did that because zero, x equals zero is where we switch, where f of x switches from being x plus one to cosine pi x.