#include <bits/stdc++.h>
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)

using namespace std;
using mint = modint998244353;

int main() {
    int n;
    string s;
    cin >> n >> s;
    
    vector<mint> dp(n+1);
    dp[0] = 1;
    rep(i, n) {
        int m = n-i;
        vector<mint> old(m);
        swap(dp, old);
        
        if (s[i] == '1') {
            rep(j, m) dp[j] = old[j]*(n-i-j);
        }
        else {
            rep(j, m) dp[j] = old[j+1]*(j+1);
            mint sum;
            rep(j, m) {
                sum += old[j];
                dp[j] += sum;
            }
        }
    }
    
    mint ans = dp[0];
    cout << ans.val() << '\n';
    
    return 0;
}