$\texttt{Slight Light, Slight Hope.}$
Little W has a rooted tree with $n$ nodes (labeled $1$ to $n$), with node $1$ as the root. The weight of node $i$ is $a_i$.
Let $f_i$ be the parent of node $i$ (for convenience, we define $f_1=0$). Little W discovered a fascinating property of this tree: for any integer $i\in[2,n]$, it holds that $f_{i-1}\le f_i < i$.
Little C is very interested in this, so she decides to perform $q$ queries. Each query $i$ provides an interval $[l_i, r_i]$, and asks to calculate:
$$ \left(\sum_{x=l_i}^{r_i}\sum_{y=l_i}^{r_i}[l_i\le \operatorname{LCA}(x,y)\le r_i]\cdot a_x\cdot a_y\right)\bmod998244353 $$
where $\operatorname{LCA}(x,y)$ denotes the lowest common ancestor of $x$ and $y$.
Since Little C is eager to know the answer for each query, this problem is forced to be online (see the Input section for details).
Input
The first line contains two positive integers $n$ and $q$, representing the number of nodes and the number of queries, respectively.
The second line contains $n$ non-negative integers $a_{1\sim n}$, representing the weights of each node.
The third line contains $n-1$ positive integers $f_{2\sim n}$, representing the parent of each node.
The next $q$ lines each contain two non-negative integers $l_i', r_i'$. Let $lst$ be the answer to the previous query (for the first query, $lst=0$). The actual values are $l_i = l_i' \oplus lst$ and $r_i = r_i' \oplus lst$, where $\oplus$ denotes the bitwise XOR operation.
Output
Output $q$ lines, each containing an integer representing the answer to the corresponding query (modulo $998244353$).
Examples
Input 1
6 3
1 2 3 4 5 6
1 1 2 2 3
1 2
11 12
131 132
Output 1
9
130
441
Note 1
For the first query, the interval is $[1,2]$. $\operatorname{LCA}(1,1)=1$, $\operatorname{LCA}(1,2)=1$, $\operatorname{LCA}(2,1)=1$, $\operatorname{LCA}(2,2)=2$, all of which satisfy the condition. The answer is $1\times 1+1\times2+2\times1+2\times2=9$.
For the second query, the interval is $[2,5]$. $\operatorname{LCA}(2,2)=2$, $\operatorname{LCA}(2,4)=2$, $\operatorname{LCA}(2,5)=2$, $\operatorname{LCA}(3,3)=3$, $\operatorname{LCA}(4,2)=2$, $\operatorname{LCA}(4,4)=4$, $\operatorname{LCA}(4,5)=2$, $\operatorname{LCA}(5,2)=2$, $\operatorname{LCA}(5,4)=2$, $\operatorname{LCA}(5,5)=5$ satisfy the condition, while the remaining pairs have an $\operatorname{LCA}$ of $1$. The answer is $130$.
For the third query, the interval is $[1,6]$. Since the $\operatorname{LCA}$ is guaranteed to be in the range $[1,n]$, all pairs satisfy the condition. The answer is $441$.
Constraints
- Subtask $1$ ($20\%$): $n,q \leq 5\times10^3$
- Subtask $2$ ($20\%$): $n,q \leq 5\times10^4$
- Subtask $3$ ($20\%$): The tree structure is random
- Subtask $4$ ($40\%$): No special constraints
For $100\%$ of the data, $1\le n,q\le2.5\times10^5$, $0\le a_i < 998244353$, $1\le l_i\le r_i\le n$. It is guaranteed that for any integer $i\in[2,n]$, $f_{i-1}\le f_i < i$ holds.