I know. You want that 100k, and easy obvious set theory questions are an alluring source of points. But for the love of god, some questions are so obviously natural that it would be ridiculous to assume no one bothered to ask them in the course of nearly 8 years. I put less effort than you did in closing this question, which says something about you. Seriously man. —
Asaf Karagila 32 secs ago