And then a 13 is an A, and it's in the set of all things in the universe that are neither a 0 or a blue. So we could throw a 13 in there. So we've simplified things a good bit. This whole crazy business, all of this crazy business, has simplified to this set right over here. Now, we want to find the relative complement of this business in A. So let me pick another color here. So we want to find the relative complement of this business in A.