AtCoder Grand Contest 067
E
Biconnected Graph
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Problem Statement

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You are given an integer $N$ and a prime $P$.

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Count the number, modulo $P$, of undirected connected graphs $G$ of $N$ vertices numbered $1$ to $N$ that satisfy the following condition:

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  • There are no self-loops in $G$. Note that multiple edges are allowed.
  • For all edges $(u,v)$ in $G$, if we delete $(u,v)$ from $G$, $G$ remains connected. In other words, $G$ is edge-biconnected.
  • For all edges $(u,v)$ in $G$, if we delete $(u,v)$ from $G$, $G$ is no longer edge-biconnected.
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Two graphs are considered different if and only if there exists a pair of distinct vertices $(u,v)$ such that the numbers of edges connecting $u$ and $v$ in the two graphs are different.

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Constraints

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  • $2 \le N \le 50$
  • $10^9<P<1.01\times 10^9$
  • $P$ is prime.
  • All input values are integers.
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Input

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Input is given from Standard Input in the following format:

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N P

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Output

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Print the answer.

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样例

Input #1
2 1005976817
Output #1
1
Input #2
5 1000837403
Output #2
372
Input #3
10 1001160547
Output #3
789846604
Input #4
20 1006779551
Output #4
888612770
题目信息
题号
agc067_e
时间限制
3 s
内存限制
1024 MB

题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。