#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int N = 2010, mod = 998244353;

int n;
ll dp[N][N], d[N];
string s;

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