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>
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma comment(linker, "/STACK:1024000000,1024000000")
using namespace std;
long long x, y, z, dp[505][505], color[505];
long long Dynamic_Rec(long long left, long long right) {
  if (right <= left) {
    return 1;
  }
  long long &re = dp[left][right];
  if (re != -1) {
    return re;
  }
  re = 0;
  long long n = left, n1 = 0, n2 = 0;
  for (int i = left; i <= right; i++) {
    if (color[i] < color[n]) {
      n = i;
    }
  }
  for (int i = left; i <= n; i++) {
    n1 = (n1 % 998244353 + (Dynamic_Rec(left, i - 1) % 998244353 *
                            Dynamic_Rec(i, n - 1) % 998244353) %
                               998244353) %
         998244353;
  }
  for (int i = n; i <= right; i++) {
    n2 = (n2 % 998244353 + (Dynamic_Rec(n + 1, i) % 998244353 *
                            Dynamic_Rec(i + 1, right) % 998244353) %
                               998244353) %
         998244353;
  }
  re = (n1 % 998244353 * n2 % 998244353) % 998244353;
  return re % 998244353;
}
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  ;
  memset(dp, -1, sizeof(dp));
  cin >> x >> y;
  for (int i = 1; i <= y; i++) {
    cin >> color[i];
  }
  cout << Dynamic_Rec(1, x) << endl;
  return 0;
}