#include <iostream>
#include <vector>

int main() {
    int N;
    std::cin >> N;

    std::vector<std::vector<long long>> A(N + 1, std::vector<long long>(N, 0));
    std::vector<long long> B(N, 0);
    std::string S;
    std::cin >> S;

    const int P = 998244353;
    std::vector<long long> p(N);
    
    p[0] = 1; // base case for powers of 2
    for (int i = 1; i < N; ++i) {
        p[i] = (2 * p[i - 1]) % P; // precalculate powers of 2 modulo P
    }

    for (int i = 1; i <= N; ++i) {
        bool s = S[N - i] > '0';
        for (int j = 0; j < i; ++j) {
            long long val = (s && j > 0) ? (p[std::max(0, i - j - 2)] - A[i - j - 1][j]) % P : 0;
            if (val < 0) val += P; // ensure non-negative value
            B[j] = (B[j] + val + (s && j == 0 ? p[std::max(0, i - 2)] : 0)) % P;
            A[i][j] = B[j];
        }
    }

    long long result = 0;
    for (int j = 0; j < N; ++j) {
        result = (result + p[j] * A[N][j]) % P;
    }

    std::cout << result << std::endl;
    return 0;
}