Problem Statement
Given are a sequence of $N$ positive integers $A = (A_1, A_2, \ldots, A_N)$ and $Q$ queries. The $i$-th query is as follows:
- given integers
$x_i$and$y_i$(where$1\leq x_i\leq N$), change$A_{x_i}$to$y_i$.
Each time the query changes the sequence, find the answer to the following problem modulo $998244353$ (see Notes).
Let
$f(n)$be the maximum total number of points when doing the following operation$n$times on$A$.
- Choose
$i, j$such that$A_i\leq A_j$and choose non-negative real number$x$such that$A_i + 2x \leq A_j$.- Add
$x$to$A_i$and subtract$x$from$A_j$.- Gain
$x$points.It can be proved that the limit
$\displaystyle \lim_{n\to\infty} f(n)$exists. Find this limit.
Note
We can prove that the limit in question is always a rational number. Additionally, under the Constraints of this problem, when that number is represented as $\frac{P}{Q}$ using two coprime integers $P$ and $Q$, we can prove that there is a unique integer $R$ such that $R\times Q\equiv P\pmod{998244353}$ and $0\leq R < 998244353$. Find this $R$.
Constraints
$2\leq N\leq 3\times 10^5$$1\leq Q\leq 3\times 10^5$$1\leq A_i \leq 10^9$$1\leq x_i\leq N$$1\leq y_i\leq 10^9$
Input
Input is given from Standard Input in the following format:
N Q
A_1 A_2 \ldots A_N
x_1 y_1
\vdots
x_Q y_Q
Output
Print $Q$ lines; the $i$-th line should contain the answer to the problem just after the change by the $i$-th query.
样例
3 4
7 5 5
1 5
2 6
1 7
3 5
0
1
2
2
2 4
1 2
2 5
1 3
1 2
2 3
2
1
499122178
499122177
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