https://zh.apacode.com/post/coca-cola-and-coke-are-separated-by-3-kilometers-the-two-of-them-walk-from-two-places-at-the-same-time-to-each-other-if-coca-colas-speed-is-80mmin-cokes-speed-is-70mmin-they-will-meet-in-a-few-minutes