This problem is in Contest(s) below:
Contest 1308:2023寒假下c5
Contest 1352:2024暑期246晚c4
Contest 1316:2024春周六c++c5
Contest 1214:2023春周六晚c++六期
Contest 1222:2023春周日下c++六期
Contest 1190:2022秋周日早c++6期
Contest 1187:2022秋周六晚c++6期
Contest 1133:2022年春季周六早第六期
Contest 1141:2022春季周日下第六期
Contest 1286:2024春季c++c6