Score : $500$ points
We have a rooted tree with $N$ vertices, numbered $1, 2, \dots, N$.
Vertex $1$ is the root, and the parent of Vertex $i \, (2 \leq i \leq N)$ is Vertex $P_i$.
You are given $Q$ queries. In the $i$-th query $(1 \leq i \leq Q)$, given integers $U_i$ and $D_i$, find the number of vertices $u$ that satisfy all of the following conditions:
Input is given from Standard Input in the following format:
$N$ $P_2$ $P_3$ $\ldots$ $P_N$ $Q$ $U_1$ $D_1$ $U_2$ $D_2$ $\vdots$ $U_Q$ $D_Q$
Print $Q$ lines. The $i$-th line should contain the response to the $i$-th query.
7 1 1 2 2 4 2 4 1 2 7 2 4 1 5 5
3 1 0 0
In the $1$-st query, Vertices $4$, $5$, and $7$ satisfy the conditions. In the $2$-nd query, only Vertices $7$ satisfies the conditions. In the $3$-rd and $4$-th queries, no vertice satisfies the conditions.