本题征求翻译。如果你能提供翻译或者题意简述，请[提交翻译](https://www.luogu.org/problemnew/translate/CF1108B)，感谢你的贡献。
by _•́へ•́╬_ @ 2019-01-24 10:43:19
https://www.luogu.org/discuss/show/69997
by _•́へ•́╬_ @ 2019-01-24 10:43:41