2021 年东华大学金马程序设计联赛
G. IDEA's Tree
单点时限: 10.0 sec
内存限制: 256 MB
IDEA has a tree with $n(1\leq n\leq 5000)$ nodes. Now she select a connected subgraph on the tree randomly, please help her calculate the expected size of connected subgraph she select (module $998244353$).
输入格式
There are multiple test cases.
For each test case, in the first line, there is an integer n, denoting the node number of the tree.
Then for the next $n-1$ lines, $i$-th line contains an integer $u$, indicate that there is an edge between $i+1$ and $u$.
输出格式
For each test cases, print the answer in one line.
样例
Input
3 1 1
Output
665496237
通知
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通知