#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define bitrep(i, n) for (ll i = 0; i < (1 << n); ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define yesNo(b) ((b) ? "Yes" : "No")
using ll = long long;
using ull = unsigned long long;
string alphabet = "abcdefghijklmnopqrstuvwxyz";
string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const double pi = 3.141592653589793;
int smallMOD = 998244353;
int bigMOD = 1000000007;

int main()
{
    int n;
    string s;
    cin >> n >> s;
    vector<int> A;
    if (count(all(s), '1') == 0)
    {
        cout << 0 << endl;
    }
    else
    {
        rep(i, n)
        {
            if (s[i] == '1')
                A.push_back(i);
        }
        ll ans = 1;
        rep(i, A.size() - 1)
        {
            ans *= A[i + 1] - A[i] + 1;
            ans = ans % smallMOD;
        }
        cout << ans % smallMOD << endl;
    }
    return 0;
}