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• Season 5 Update

Hello! This is solved.ac, the community powered guide for programming challenges.

On June 5, 2025, it has been five years since BOJ and solved.ac were integrated. solved.ac introduces new features and changes through season updates on an approximately yearly basis. To celebrate the 5th anniversary, we are launching the Season 5 Update.

'OVER RATING' Added (Scheduled for July)

A new rating that reflects only the 1,000 most difficult problems you have solved will be updated. This rating will be called OVER RATING and will be displayed separately from the existing AC rating.

Partial Change to AC Rating Calculation Formula

The bonus based on the number of problems solved in the AC rating calculation formula will be changed as follows.

• Previous: $\left\lfloor 175\times \left(1-0.995^{\left(\text{Number of problems solved}\right)}\right) \right\rceil$
• Changed: $\left\lfloor 200\times \left(1-0.997^{\left(\text{Number of problems solved}\right)}\right) \right\rceil$

CLASS Problem Set Changes

Some CLASS compositions have been changed as follows.

CLASS 2

• Added: #14626 〈ISBN〉
• Removed: #1654 〈랜선 자르기〉 (Moved to CLASS 3)

CLASS 3

• Added: #30802 〈랜선 자르기〉
• Removed: #6064 〈Cain Calendar〉

CLASS 5 Essentials

• Added: #1106 〈호텔〉
• Removed: #7579 〈앱〉

CLASS 7

• Added: #10538 〈The Big Painting〉
• Removed: #16163 〈#15164번_제보〉 (Moved to Essentials)

CLASS 7 Essentials

• Added: #16163 〈#15164번_제보〉
• Removed: #10266 〈Clock Pictures〉

CLASS 8

• Added: #31603 〈Tree Quiz〉
• Removed: #17975 〈Strike Zone〉

5th Anniversary Profile Badge and Background

To celebrate the 5th anniversary of solved.ac and the start of Season 5, the following profile background and badge will be added.

• Profile Badge 〈5 Solves〉
• Profile Background 〈Milestone in Hand〉

You can obtain the badge and background by solving at least one problem you have not solved before between 6:00 AM, June 5, 2025 (Thu) and 6:00 AM, June 12, 2025 (Thu). (KST) The background and badge are awarded immediately upon solving a problem.

Season 4 End Rewards

As a reward for your efforts in problem-solving during Season 4, we have given out Season 4 profile background rewards to all participants. Details are as follows.

• The background was given to everyone who was Bronze V or higher as of 6:00 AM, June 5, 2025. (KST)
• The profile background design corresponding to your tier at that time was awarded.