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 N = 510;
const int mod = 998244353;
int f[N][N];
int arr[N];
int pmin[N][N];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) cin >> arr[i];
  for (int i = 1; i <= n; i++) {
    for (int j = i; j <= n; j++) {
      if (j == i) {
        pmin[i][j] = i;
      } else {
        if (arr[pmin[i][j - 1]] > arr[j]) {
          pmin[i][j] = j;
        } else {
          pmin[i][j] = pmin[i][j - 1];
        }
      }
    }
  }
  for (int i = 0; i <= n; i++) f[i][i] = f[i + 1][i] = 1;
  for (int len = 2; len <= n; len++) {
    for (int i = 1; i + len - 1 <= n; i++) {
      int j = i + len - 1;
      int t = pmin[i][j];
      int ans1 = 0, ans2 = 0;
      for (int k = i; k <= t; k++) {
        (ans1 += 1ll * f[i][k - 1] * f[k][t - 1] % mod) %= mod;
      }
      for (int k = t; k <= j; k++) {
        (ans2 += 1ll * f[t + 1][k] * f[k + 1][j] % mod) %= mod;
      }
      f[i][j] = (1ll * ans1 * ans2) % mod;
    }
  }
  cout << f[1][n] << endl;
}