#include <bits/stdc++.h>
using namespace std;
const int MOD = 998244353;
const int MAXM = 1000005;
const int SIZE = 1005;
int orig[MAXM];
int arr[MAXM];
int memo[SIZE][SIZE];
bool been[SIZE][SIZE];
int occ1[SIZE], occ2[SIZE];
int add(int a, int b) { return (a + b) % MOD; }
int mul(int a, int b) { return (long long)a * b % MOD; }
int solve(int l, int r) {
  if (l > r) return 1;
  if (been[l][r]) return memo[l][r];
  been[l][r] = true;
  int mn = *min_element(arr + l, arr + r + 1);
  int focc = occ1[mn], locc = occ2[mn];
  if (focc < l || locc > r) return memo[l][r] = 0;
  int ml = 1;
  vector<int> occs;
  for (int i = l; i <= r; i++) {
    if (arr[i] == mn) occs.push_back(i);
  }
  for (int i = 1; i < (int)occs.size(); i++) {
    ml = mul(ml, solve(occs[i - 1] + 1, occs[i] - 1));
  }
  int sum_l = 0;
  for (int ll = l; ll <= occs[0]; ll += 1) {
    sum_l = add(sum_l, mul(solve(l, ll - 1), solve(ll, occs[0] - 1)));
  }
  int sum_r = 0;
  for (int rr = occs.back(); rr <= r; rr += 1) {
    sum_r = add(sum_r, mul(solve(occs.back() + 1, rr), solve(rr + 1, r)));
  }
  int ans = mul(ml, mul(sum_r, sum_l));
  return memo[l][r] = ans;
}
int main() {
  int n, m;
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d", &orig[i]);
  }
  int real_m = 0;
  for (int i = 1; i <= n; i++) {
    if (orig[i] != orig[i - 1]) {
      arr[++real_m] = orig[i];
    }
  }
  for (int i = 1; i <= real_m; i++) {
    occ2[arr[i]] = i;
    if (occ1[arr[i]] == 0) occ1[arr[i]] = i;
  }
  if (real_m > 2 * n) {
    return 0 * puts("0");
  }
  printf("%d\n", solve(1, n));
  return 0;
}
