Welcome to **UOJ $\Sigma^\ast$ Round #1** !↵
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We are pleased to invite you to [UOJ Σ* Round #1](https://uoj.ac/contest/96), which will be held on [Sunday, April 13, 2025 at 17:00 (UTC+8)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=UOJ+%CE%A3%2A+Round+%231&iso=20250413T17&p1=237&ah=5).↵
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There will be **3 problems** with subtasks, and **5 hours** for you to solve them under UOJ rules (similar to IOI, but pretests are used during contest rather than system tests).↵
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UOJ $\Sigma^\ast$ Round is a series of contest held by [user:CommonAnts,2025-04-12] on [UOJ](https://uoj.ac/), thanks to everyone for your contribution.↵
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I'm sorry that the statements are provided only in Chinese language, although AI translation is useable nowadays.↵
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> In formal language, $\Sigma^*$ represents the set of "all" strings. Can you find the answer to the problem in the ocean of countless characters?↵
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[Contest Link](http://uoj.ac/contest/96)↵
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UOJ $\Sigma^\ast$ Round #1 is authored and prepared by [user:CommonAnts,2025-04-12] et al, with difficulty at about $2100, 2800, 3500$ on Codeforces (I think so).↵
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The top three participants and a special participant with condition of SHA256 `48405573d9ac7a841e4860fab6036961bd8a2e7404027595e7a84b47c7771b6b` will get our special gift.↵
↵
PS. [user:CommonAnts,2025-04-12] is now working on algorithms and computer science educational research, including competitive programming. Interested ones may contact us.↵
↵
↵
We are pleased to invite you to [UOJ Σ* Round #1](https://uoj.ac/contest/96), which will be held on [Sunday, April 13, 2025 at 17:00 (UTC+8)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=UOJ+%CE%A3%2A+Round+%231&iso=20250413T17&p1=237&ah=5).↵
↵
There will be **3 problems** with subtasks, and **5 hours** for you to solve them under UOJ rules (similar to IOI, but pretests are used during contest rather than system tests).↵
↵
UOJ $\Sigma^\ast$ Round is a series of contest held by [user:CommonAnts,2025-04-12] on [UOJ](https://uoj.ac/), thanks to everyone for your contribution.↵
↵
↵
↵
[Contest Link](http://uoj.ac/contest/96)↵
==================↵
↵
UOJ $\Sigma^\ast$ Round #1 is authored and prepared by [user:CommonAnts,2025-04-12] et al, with difficulty at about $2100, 2800, 3500$ on Codeforces (I think so).↵
↵
The top three participants and a special participant with condition of SHA256 `48405573d9ac7a841e4860fab6036961bd8a2e7404027595e7a84b47c7771b6b` will get our special gift.↵
↵
PS. [user:CommonAnts,2025-04-12] is now working on algorithms and computer science educational research, including competitive programming. Interested ones may contact us.↵
↵
