This problem is in Contest(s) below:
Contest 1215:2023春周六晚日早c++七期
Contest 1295:2023秋季c++c7
Contest 1045:数学数论1
Contest 1006:分治算法
Contest 1365:2024秋周五晚c4
Contest 1191:2022秋周日下c++8期
Contest 1184:2022秋周六早c++8期
Contest 1193:2022秋国庆集训
Contest 1345:2024暑期135下c4
Contest 1352:2024暑期246晚c4
Contest 1316:2024春周六c++c5
Contest 1190:2022秋周日早c++6期
Contest 1187:2022秋周六晚c++6期
Contest 1214:2023春周六晚c++六期
Contest 1222:2023春周日下c++六期
Contest 1286:2024春季c++c6
Contest 1203:2023春周日早C++第4期(平阳)