P25879 [AtCoder] Flipping Coins 2
NOI
题目描述

Problem Statement

$N coins numbered 0,1,\ldots,N-1$ are arranged in a row. Initially, all coins are face up. Also, you are given a sequence A of length N consisting of integers between 0 and N-1.
Snuke will choose $a permutation p=(p_1,p_2,\ldots,p_N)$ of $(1,\ldots,N)$ at equal probability and perform N operations. In the $i-th (1\leq i \leq N)$ operation,

  • he flips (A_{p_i}+1) coins: coin $(i-1) \bmod N, coin (i-1+1 ) \bmod N, \ldots$, and coin $(i -1+ A_{p_i}) \bmod N$.

After the N operations, Snuke receives k yen (the currency in Japan) from his mother, where k is the number of face-up coins.
Find the expected value, modulo 998244353, of the money Snuke will receive.

Definition of expected value modulo 998244353
In this problem, we can prove that the sought expected value is always a rational number.
Moreover, under the Constraints of this problem, when the sought expected value is represented as an irreducible fraction $\frac{y}{x}$, it is guaranteed that x is indivisible by 998244353.
Then, an integer z between 0 and 998244352 such that xz $\equiv y \pmod{998244353}$ is uniquely determined. Find such z.

Input

The input is given from Standard Input in the following format:
N
$A_1 A_2 \ldots A_N$

Output

Print the answer.

Constraints

  • $1 \leq N\leq 2\times 10^5$
  • $0\leq A_i \leq N-1$
  • All values in the input are integers.

Sample Input 1

2
0 1

Sample Output 1

1

p can be either (1,2) or (2,1).

  • If (1,2) is chosen as p:

In the first operation, coin 0 is flipped, and in the second operation, coin 1 and coin 0 are flipped. One coin, coin 0, results in being face up, so he receives 1 yen.

  • If (2,1) is chosen as p:

In the first operation, coin 0 and coin 1 are flipped, and in the second operation, coin 1 is flipped. One coin, coin 1, results in being face up, so he receives 1 yen.
Therefore, the expected value of the money he receives is 1 yen.

Sample Input 2

4
3 1 1 2

Sample Output 2

665496237

Print the expected value modulo 998244353.

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
2 0 1
样例输出
1