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

int main() {
    int N;
    string A;
    cin >> N >> A;

    int first_zero = -1;
    int last_one = -1;

    for (int i = 0; i < N; i++) {
        if (A[i] == '0' && first_zero == -1) {
            first_zero = i;
        }
        if (A[i] == '1') {
            last_one = i;
        }
    }

    if (first_zero == -1 || last_one == -1) {
        cout << 1 << endl;
        return 0;
    }

    int ans = max(0, last_one - first_zero);
    cout << ans % 998244353 << endl;

    return 0;
}