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

using i64 = long long;
const int N = 2e3 + 10, P = 998244353;

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

string s;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> n >> s;
    dp[n] = 1;
    for(int i = 0; i < n; i ++) {
        if(s[i] == '0') {
            for(int j = n, p = 0; j >= 0; j --) {
                p += dp[j];
                dp[j] = ((i64)dp[j] * (n - i - j) + p - dp[j]) % P;
                p %= P;
            }
        }else{
            for(int j = 0; j <= n; j ++)
                dp[j] = dp[j + 1] * (j + 1ll) % P;
        }
    }
    cout << accumulate(dp, dp + n + 1, 0ll) % P;
}