#include <iostream>
#include <vector>

const int P = 998244353;

int main() {
    int N;
    std::cin >> N;
    std::vector<std::vector<long long>> A(N+1, std::vector<long long>(N));
    std::vector<long long> B(N), p(N);
    std::string S;
    std::cin >> S;

    // Precompute powers of 2 modulo P
    p[0] = 1;
    for (int i = 1; i < N; i++) {
        p[i] = (p[i-1] * 2) % P;
    }

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

    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;
}