Petrozavodsk Winter 2022. Day 4. Almost Northern Contest

Note: problems were selected from the following contest:

Nordic Collegiate Programming Contest 2021
The 2021 Benelux Algorithm Programming Contest / United Kingdom and Ireland Programming Contest 2021
CTU Open Contest 2021

The title of the problems has been changed, so please use the ID (A, B, etc.) to identify the problem.

注意：题目是从以下比赛中选择的：

Nordic Collegiate Programming Contest 2021
The 2021 Benelux Algorithm Programming Contest / United Kingdom and Ireland Programming Contest 2021
CTU Open Contest 2021

题目的标题有所变化，所以请使用题目编号（如 A, B 等）来辨别题目。

Problem