#include <iostream>
#include <vector>
#include <string>

using namespace std;

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

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

    const long long MOD = 998244353;

    vector<bool> L(N);
    bool found0 = false;
    for (int i = 0; i < N; ++i) {
        if (A[i] == '0') found0 = true;
        L[i] = found0;
    }

    vector<bool> R(N);
    bool found1 = false;
    for (int i = N - 1; i >= 0; --i) {
        if (A[i] == '1') found1 = true;
        R[i] = found1;
    }

    vector<vector<long long>> dp(N, vector<long long>(2, 0));

    if (L[0]) dp[0][0] = 1;
    if (R[0]) dp[0][1] = 1;

    for (int i = 1; i < N; ++i) {
        if (L[i]) {
            dp[i][0] = (dp[i][0] + dp[i-1][0]) % MOD;
            if (A[i-1] == '1' && A[i] == '0') {
                dp[i][0] = (dp[i][0] + dp[i-1][1]) % MOD;
            }
        }
        if (R[i]) {
            dp[i][1] = (dp[i][1] + dp[i-1][0]) % MOD;
            dp[i][1] = (dp[i][1] + dp[i-1][1]) % MOD;
        }
    }

    cout << (dp[N-1][0] + dp[N-1][1]) % MOD << endl;

    return 0;
}