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

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

    int N;
    cin >> N;
    string A;
    cin >> A;

    vector<bool> prefix_zero(N+1, false);
    vector<bool> suffix_one(N+2, false);

    for (int i = 1; i <= N; i++) {
        prefix_zero[i] = prefix_zero[i-1] || (A[i-1] == '0');
    }

    for (int i = N; i >= 1; i--) {
        suffix_one[i] = suffix_one[i+1] || (A[i-1] == '1');
    }

    int K = 0;
    for (int i = 1; i <= N; i++) {
        if (prefix_zero[i] && suffix_one[i]) K++;
    }

    cout << (K + 1) % 998244353 << '\n';
}