1841F

[原题](https://codeforces.com/contest/1841/problem/F) [翻译](https://www.luogu.com.cn/problem/CF1841F) 算是一道很经典的题了，所以决定写博客 设最后选出的四种生物个数分别是$A$,$B$,$C$,$D$，则 ......