Hi, Codeforces!

We are so happy to invite you to participant in The 20th Southeast University Programming Contest (Summer), which will start at May/26/2024 09:00 (Moscow time).

This round will be conducted according to ACM/ICPC rules. Therefore, solutions will be judged on all test points during the competition.

The competition is team-based, with teams of 1 to 3 people, and you will be given 11 to 13 problems and 5 hours to solve them.

Please note that the penalty for submitting an incorrect answer in this competition is 20 minutes.

All questions were created and written by me and Ram_seu.

I would like to thank:
1. CPC club of Southeast University and seuOJ.
2. Southeastern university Science and Technology Association of Jiruanzhi schools for all the works and all the staff involved in this contest.
3. king_of_gamers,jackylova,Tobo,xukuan,thisislike_fan,CoffeeFish,9756 for testing this round and giving useful feedback.
4. Last but not least, You for participating in this round.

Good luck and have fun!

In this problem H. Tree Diameter 's tag, we could find its difficulty is 2000, but actually it is the last problem of a div1+div2 round. Is this a mistake?