Hello Codeforces!

I am glad to invite you to InfOJ April Fools Day Contest 2025 (IAFDC for short) which will start on April 5th 2025, 19:00 UTC+8.

The contest will last for 2.5 hours with 10 tasks for you to solve. All problems are worth 100 points, and the contest will be in IOI mode.

Since 2021, InfOJ has held four April Fool's Contests. Each year, we uphold the mission of "expanding the boundaries of the online judging system" and present freshly eye-opening problems to a wide range of participants, both with and without competitive programming background. We are committed to leveraging the versatility of the open-source UOJ System (which InfOJ is based on) to provide testing for problems that cannot be judged on other online judging systems. Here are some examples of such problems:

• Problem A from IAFDC 2024 Statement: you need to print an integer in $$$[0,10^9]$$$. [spoiler][/spoiler]