#include <bits/stdc++.h>

using namespace std;

#define int long long

const int N = 2e3 + 5, mod = 998244353;

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

char a[N];

signed main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  dp[0][n] = 1;
  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 (a[i] == '0') {
        dp[i][j] = sum[i - 1][j + 1] + dp[i - 1][j] * (n - i + 1 - j) % mod;
        dp[i][j] %= mod;
      }
      else {
        dp[i][j] = (j + 1) * dp[i - 1][j + 1] % mod;
      }
    }
    for (int j = n; j >= 0; j--) {
      sum[i][j] = sum[i][j + 1] + dp[i][j];
      sum[i][j] %= mod;
    }
  }
  cout << dp[n][0];
  return 0;
}