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;
using ll = long long;
using VL = vector<ll>;
using VVL = vector<VL>;
using VI = vector<int>;
const ll MOD = 998244353;
int n;
VI C;
VVL sencer, tallat;
ll T(int e, int d);
ll S(int e, int d) {
  if (e > d) return 1;
  ll& res = sencer[e][d];
  if (res != -1) return res;
  int p = e;
  for (int i = e; i <= d; ++i)
    if (C[i] < C[p]) p = i;
  return res = (T(e, p - 1) * T(p + 1, d)) % MOD;
}
ll T(int e, int d) {
  if (e > d) return 1;
  ll& res = tallat[e][d];
  if (res != -1) return res;
  res = 2 * S(e, d);
  for (int i = e; i < d; ++i) res = (res + S(e, i) * S(i + 1, d)) % MOD;
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int mx;
  cin >> mx >> n;
  C = VI(n);
  for (int& c : C) cin >> c;
  sencer = tallat = VVL(n, VL(n, -1));
  cout << S(0, n - 1) << endl;
}