#include <iostream>
#include <vector>

using namespace std;

const int MAXN = 2005, Mod = 998244353;

string s;
int T, n, m, a[MAXN], dp[MAXN][MAXN], d[MAXN][MAXN];

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