#include<bits/stdc++.h>
using namespace std;

const int MAXN = 2001, MOD = 998244353;

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

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