CF1067E.Random Forest Rank

普及/提高-

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题目描述

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

Given a tree. Each edge of this tree will be deleted with probability 1/21/2 , all these deletions are independent. Let EE be the expected rank of resulting forest. Find E2n1E \cdot 2^{n-1} modulo 998244353998244353 (it is easy to show that E2n1E \cdot 2^{n-1} is an integer).

输入格式

First line of input contains nn ( 1n51051 \le n \le 5 \cdot 10^{5} ) — number of vertices.

Next n1n-1 lines contains two integers uu vv ( 1u,vn;uv1 \le u, \,\, v \le n; \,\, u \ne v ) — indices of vertices connected by edge.

It is guaranteed that given graph is a tree.

输出格式

Print one integer — answer to the problem.

输入输出样例

  • 输入#1

    3
    1 2
    2 3
    

    输出#1

    6
    
  • 输入#2

    4
    1 2
    1 3
    1 4
    

    输出#2

    14
    
  • 输入#3

    4
    1 2
    2 3
    3 4
    

    输出#3

    18
    
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