Problem
A 鸽子（pigeon）
B 排列（permutation）
C 树（tree）
D 军队（army）

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国庆欢乐赛3

Status: Done
Rule: OI
Problem: 4
Start at: 2024-10-5 14:00
End at: 2024-10-5 17:30
Duration: 3.5 hour(s)
Host: root
Partic.: 36