But I'll just kind of, just to draw it, that's our set C right over there. And let's think about what is a member of C and what is not a member of C. So we know that negative five is a member of our set C. This little symbol right here, this denotes membership. Membership, it looks a lot like the Greek letter epsilon, but it is not the Greek letter epsilon. This just literally means membership of a set. We know that zero is a member of set of, sorry. We know that zero is a member of our set. We know that seven is a member, is a member of our set.