Codeforces Round 518 (Div. 1) [Thanks, Mail.Ru!]
E
Random Forest Rank
Codeforces
2800
原题
← D→
翻译中…

Let's define rank of undirected graph as rank of its adjacency matrix in $\mathbb{R}^{n \times n}$.

翻译中…

Given a tree. Each edge of this tree will be deleted with probability $1/2$, all these deletions are independent. Let $E$ be the expected rank of resulting forest. Find $E \cdot 2^{n-1}$ modulo $998244353$ (it is easy to show that $E \cdot 2^{n-1}$ is an integer).

翻译中…

Input

翻译中…

First line of input contains $n$ ($1 \le n \le 5 \cdot 10^{5}$) — number of vertices.

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Next $n-1$ lines contains two integers $u$ $v$ ($1 \le u, \,\, v \le n; \,\, u \ne v$) — indices of vertices connected by edge.

翻译中…

It is guaranteed that given graph is a tree.

翻译中…

Output

翻译中…

Print one integer — answer to the problem.

翻译中…

样例

Input #1
3
1 2
2 3
Output #1
6
InputCopy OutputCopy
Input #2
4
1 2
1 3
1 4
Output #2
14
InputCopy OutputCopy
Input #3
4
1 2
2 3
3 4
Output #3
18
InputCopy OutputCopy
题目信息
题号
1067E
时间限制
3 s
内存限制
512 MB
标签
动态规划
图匹配
数学
树

题面与样例版权归 Codeforces 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。