P23419 [AtCoder] Nondivisible Prefix Sums
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题目描述

Problem Statement

You are given a prime number P, which you don't like.
Let's call an array of integers $A_1, A_2, \dots, A_N$ good, if it is possible to reorder the elements in such a way that no prefix sum is divisible by P (that is, there is no i with $1 \le i \le N$ and $A_1 + A_2 + \dots + A_i \equiv 0 \bmod P$ after the reordering).
Consider all (P-1)^N arrays of length N with elements from 1 to P-1. How many of them are good?
As this number can be very big, output it modulo 998244353.

Input

Input is given from Standard Input in the following format:
N P

Output

Output the number of good arrays modulo 998244353.

Constraints

  • $1 \le N \le 5000$
  • $2 \le P \le 10^8$
  • P is a prime.

Sample Input 1

2 5

Sample Output 1

12

There are 12 good arrays: [1, 1], [1, 2], [1, 3], [2, 1], [2, 2], [2, 4], [3, 1], [3, 3], [3, 4], [4, 2], [4, 3], [4, 4].

Sample Input 2

4 3

Sample Output 2

8

There are 8 good arrays: [1, 1, 1, 2], [1, 1, 2, 1], [1, 2, 1, 1], [2, 1, 1, 1], [2, 2, 2, 1], [2, 2, 1, 2], [2, 1, 2, 2], [1, 2, 2, 2].

Sample Input 3

5000 99999989

Sample Output 3

51699346

Sample Input 4

2021 307

Sample Output 4

644635349

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 5
样例输出
12