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

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

    vector<bool> A1(N, false);
    vector<bool> A2(N, false);

    bool ok = false;
    for (int i = 0; i < N; ++i) {
        if (A[i] == '0') ok = true;
        if (ok) A1[i] = true;
    }

    bool ok1 = false;
    for (int i = N - 1; i >= 0; --i) {
        if (A[i] == '1') ok1 = true;
        if (ok1) A2[i] = true;
    }

    long long K = 0;
    for (int i = 0; i < N; ++i) {
        if (A1[i] && A2[i]) {
            K++;
        }
    }

    cout << (K + 1) % 998244353 << endl;

    return 0;
}