Hello Codeforces!

We will hold AFOI 2025 & AFO OI Round 1 on Luogu. This is a rated unofficial contest. English statement will not be provided. You may use AI for translation.

Note that we do not guarantee that the problems are arranged in increasing order of difficulty.

• Start time: June 6 13:00 (UTC+8)
• Duration: 4.5 hours
• System: IOI
• Difficulty: similar to CF div.2
• Coordinator: Gold14526
• Writers: s4CRIF1CbUbbL3AtIAly, Tian36309, CRH826, ink65536, OierTSN, Recall_cpp
• Testers: liyuteng200909, ink65536, Tian36309, AeeE5x, CRH826
• Rated range: [0,2000] on Luogu
• Score distribution: (50+50)+100+100+100+100+100

We are looking forward to your participation!

Fun fact: all the problems have names that appeared in CNOI official contests in 2025.

• A tutorial on using Luogu (Please note that #pragma GCC optimize is temporarily banned for some reason on Luogu.)
• A brief introduction to Chinese NOI