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 = 507;
const long long mod = 998244353;
long long dp[N][N];
int c[N], st[N][20], pos[N];
int n, m;
void build() {
  for (int i = 1; i <= n; i++) {
    st[i][0] = c[i];
  }
  for (int j = 1; j <= 10; j++)
    for (int i = 1; i <= n; i++)
      st[i][j] = min(st[i][j - 1], st[i + (1 << (j - 1))][j - 1]);
}
int get(int l, int r) {
  int pow = int(log2((r - l + 1)));
  return min(st[l][pow], st[r - (1 << pow) + 1][pow]);
}
long long top_down(int l, int r) {
  if (l == r || l > r) return 1;
  if (dp[l][r]) return dp[l][r];
  int mn = pos[get(l, r)];
  long long left = 0, right = 0;
  for (int i = l; i <= mn; i++) {
    left += top_down(l, i - 1) * top_down(i, mn - 1);
    left %= mod;
  }
  for (int i = mn; i <= r; i++) {
    right += top_down(mn + 1, i) * top_down(i + 1, r);
    right %= mod;
  }
  dp[l][r] = (left % mod) * (right % mod);
  dp[l][r] %= mod;
  return dp[l][r];
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    scanf("%d", &c[i]);
    pos[c[i]] = i;
  }
  build();
  cout << top_down(1, n);
}