https://blog.wongcw.com/2020/08/01/aoc%e6%8e%a8%e5%87%ba2%e6%ac%beagon%e9%81%8a%e6%88%b2%e9%a1%af%e7%a4%ba%e5%99%a8%e5%88%86%e5%88%a5%e6%8e%a1%e7%94%a8tn%e5%92%8cnanoips%e9%9d%a2%e6%9d%bf/