P25688 [AtCoder] Nim Counting
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题目描述

Problem Statement

Given are positive integers N, K, and a sequence of $K integers (A_1, A_2, \ldots, A_K)$.
Takahashi and Aoki will play a game with stones. Initially, there are some heaps of stones, each of which contains one or more stones. The players take turns doing the following operation, with Takahashi going first.

  • Choose a heap with one or more stones remaining. Remove any number of stones between 1 and X (inclusive) from that heap, where X is the number of stones remaining.

The player who first gets unable to do the operation loses.
Now, consider the initial arrangements of stones satisfying the following.

  • $1\leq M\leq N$ holds, where M is the number of heaps of stones.
  • The number of stones in each heap is one of the following: $A_1, A_2, \ldots, A_K$.

Assuming that the heaps are ordered, there are $K+K^2+\cdots +K^N$ such initial arrangements of stones. Among them, find the number, modulo 998244353, of arrangements that lead to Takahashi's win, assuming that both players play optimally.

Input

Input is given from Standard Input in the following format:
N K
$A_1 A_2 \ldots A_K$

Output

Print the answer.

Constraints

  • $1 \leq N \leq 2\times 10^5$
  • $1 \leq K < 2^{16}$
  • $1 \leq A_i < 2^{16}$
  • All A_i are distinct.
  • All values in input are integers.

Sample Input 1

2 2
1 2

Sample Output 1

4

There are six possible initial arrangements of stones: (1), (2), (1,1), (1,2), (2,1), and (2,2).
Takahashi has a winning strategy for four of them: (1), (2), (1,2), and (2,1), and Aoki has a winning strategy for the other two. Thus, we should print 4.

Sample Input 2

100 3
3 5 7

Sample Output 2

112184936

Be sure to find the count 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 2 1 2
样例输出
4