Problem: This is the first subtask of problem F. The only differences between this and the second subtask are the constraints on the value of m and the time limit. You need to solve both subtasks in order to hack this one.

There are n+1 distinct colours in the universe, numbered 0 through n. There is a strip of paper m centimetres long initially painted with colour 0. 

Alice took a brush and painted the strip using the following process. For each i from 1 to n, in this order, she picks two integers 0 ≤ a_i < b_i ≤ m, such that the segment [a_i, b_i] is currently painted with a single colour, and repaints it with colour i. 

Alice chose the segments in such a way that each centimetre is now painted in some colour other than 0. Formally, the segment [i-1, i] is painted with colour c_i (c_i ≠ 0). Every colour other than 0 is visible on the strip.

Count the number of different pairs of sequences \\{a_i\}_{i=1}^n, \\{b_i\}_{i=1}^n that result in this configuration. 

Since this number may be large, output it modulo 998244353.

Input

The first line contains a two integers n, m (1 ≤ n ≤ 500, n = m) — the number of colours excluding the colour 0 and the length of the paper, respectively.

The second line contains m space separated integers c_1, c_2, …, c_m (1 ≤ c_i ≤ n) — the colour visible on the segment [i-1, i] after the process ends. It is guaranteed that for all j between 1 and n there is an index k such that c_k = j.

Note that since in this subtask n = m, this means that c is a permutation of integers 1 through n.

Output

Output a single integer — the number of ways Alice can perform the painting, modulo 998244353.

Examples

Input


3 3
1 2 3


Output


5


Input


7 7
4 5 1 6 2 3 7


Output


165

Note

In the first example, there are 5 ways, all depicted in the figure below. Here, 0 is white, 1 is red, 2 is green and 3 is blue.

<image>

Below is an example of a painting process that is not valid, as in the second step the segment 1 3 is not single colour, and thus may not be repainted with colour 2.

<image>

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
const int MOD = 998244353;
const int MAX = 502;
int N, M;
int c[MAX];
int dp[MAX][MAX];
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> N >> M;
  for (int i = 1; i <= M; i++) {
    cin >> c[i];
    c[i]--;
  }
  for (int l = 1; l <= N + 1; l++) {
    for (int r = 0; r <= l; r++) {
      dp[l][r] = 1;
    }
  }
  for (int sz = 2; sz <= N; sz++) {
    for (int l = 1; l + sz - 1 <= N; l++) {
      int r = l + sz - 1;
      int m = l;
      for (int i = l; i <= r; i++) {
        if (c[i] < c[m]) {
          m = i;
        }
      }
      cerr << "lowest colour in [" << l << ", " << r << "]: " << m << '\n';
      int left = 0;
      for (int a = l; a <= m; a++) {
        left += 1LL * dp[l][a - 1] * dp[a][m - 1] % MOD;
        left %= MOD;
      }
      int right = 0;
      for (int b = m; b <= r; b++) {
        right += 1LL * dp[m + 1][b] * dp[b + 1][r] % MOD;
        right %= MOD;
      }
      dp[l][r] = 1LL * left * right % MOD;
    }
  }
  cout << dp[1][N] << '\n';
  return 0;
}