P4942 [CF1067E] Random Forest Rank
NOI
题目描述

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

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).

Input

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

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

It is guaranteed that given graph is a tree.

Output

Print one integer — answer to the problem.

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
3 1 2 2 3
样例输出
6