There is a tree with $n$ vertices, labeled from $1$ to $n$.
For each vertex in the tree, there may be a white piece, a black piece, or no piece. There are exactly $w$ white pieces and $b$ black pieces on the tree. Additionally, for every pair of vertices with pieces of the same color, there exists a path such that every vertex on the path contains a piece of the same color (i.e., pieces of each color form a connected component).
You can perform the following operation any number of times:
- Choose a vertex $u$ that contains a piece.
- Choose a path $p_1, p_2, \dots, p_k$ such that $p_1 = u$, all vertices $p_1, p_2, \dots, p_{k-1}$ contain pieces of the same color, and $p_k$ has no piece.
- Move the piece from $p_1$ to $p_k$. After this, $p_1$ has no piece, and $p_k$ has a piece.
After each operation, the pieces of each color must still form a connected component.
For two initial states $S$ and $T$, we consider $S$ and $T$ to be equivalent if you can transform $S$ into $T$ using the above operations any number of times (possibly zero).
Define $f(w, b)$ as the number of equivalence classes when there are $w$ white pieces and $b$ black pieces on the tree. You need to calculate:
$$(\sum_{w=1}^{n-1}\sum_{b=1}^{n-w} f(w,b) \cdot w \cdot b) \bmod 10^9+7$$
Input
The first line contains an integer $T$, representing the number of test cases.
For each test case:
The first line contains an integer $n$, representing the size of the tree.
The second line contains $n-1$ integers $fa_i$ for $i=2 \dots n$ ($1 \le fa_i < i$), representing an edge between $(fa_i, i)$ in the tree.
Output
For each test case, output a single integer representing the answer.
Examples
Input 1
2 5 1 2 3 3 10 1 2 3 4 3 6 3 8 2
Output 1
71 989
Note
For the first example:
- $f(1, 1) = 1, f(1, 2) = 2, f(1, 3) = 3, f(1, 4) = 3,$
- $f(2, 1) = 2, f(2, 2) = 2, f(2, 3) = 1,$
- $f(3, 1) = 3, f(3, 2) = 1,$
- $f(4, 1) = 3.$
Constraints
For all test cases: $n \ge 2, 1 \le \sum n \le 2 \times 10^5, 1 \le fa_i < i$.
| Subtask | $\sum n \le$ | Special Property | Score |
|---|---|---|---|
| $1$ | $10$ | None | $12$ |
| $2$ | $2 \times 10^5$ | $fa_i = 1$ | $8$ |
| $3$ | $2 \times 10^5$ | $n=2^k-1, fa_i = \lfloor \frac{i}{2} \rfloor$ | $15$ |
| $4$ | $2 \times 10^5$ | There exist positive integers $k, m$ such that $n=mk+1, fa_i = \max(1, i-k)$ | $15$ |
| $5$ | $500$ | None | $10$ |
| $6$ | $3000$ | None | $15$ |
| $7$ | $2 \times 10^5$ | None | $25$ |