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

const int MOD = 998244353;

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

    vector<int> has_zero_left(N, 0);
    vector<int> has_one_right(N, 0);

    // prefix: zero
    for (int i = 0; i < N; i++) {
        if (A[i] == '0') {
            has_zero_left[i] = 1;
        }
        if (i > 0) {
            has_zero_left[i] |= has_zero_left[i - 1];
        }
    }

    // suffix: one
    for (int i = N - 1; i >= 0; i--) {
        if (A[i] == '1') {
            has_one_right[i] = 1;
        }
        if (i < N - 1) {
            has_one_right[i] |= has_one_right[i + 1];
        }
    }

    int free_cnt = 0;

    for (int i = 0; i < N; i++) {
        if (has_zero_left[i] && has_one_right[i]) {
            free_cnt++;
        }
    }

    // compute 2^free_cnt mod
    long long ans = 1;
    for (int i = 0; i < free_cnt; i++) {
        ans = (ans * 2) % MOD;
    }

    cout << ans << endl;
    return 0;
}