#include <bits/stdc++.h>
#define _1 (__int128)1

using namespace std;
using ll = long long;

void FileIO (const string s) {
  freopen(string(s + ".in").c_str(), "r", stdin);
  freopen(string(s + ".out").c_str(), "w", stdout);
}

const int N = 2010, mod = 998244353;

int n, dp[N][N], sum[N][N];
string s;

signed main () {
  ios::sync_with_stdio(0), cin.tie(0);
  // FileIO("");
  cin >> n >> s, s = " " + s;
  for (int i = 1; i <= n; i++) sum[0][i] = 1;
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j <= n; j++) {
      if (s[i] == '0')
        dp[i][j] = (1ll * dp[i - 1][j] * (n - i - j + 1) + sum[i - 1][j + 1]) % mod;
      else
        dp[i][j] = 1ll * (j + 1) * dp[i - 1][j + 1] % mod;
    }
    for (int j = n; j; j--) sum[i][j] = (sum[i][j + 1] + dp[i][j]) % mod;
  }
  cout << dp[n][0];
  return 0;
}