#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#include <atcoder/modint>
using namespace atcoder;
using mint = modint998244353;

#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

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

  mint ans = 0;
  ll dp[4010];
  for (ll k = 0; k < N; k++)
  {
    dp[0] = 1;
    for (int i = 1; i <= N; i++)
    {
      dp[i] = 0;
    }

    for (int i = 0; i < N; i++)
    {
      ll tmp = 0;
      if (i - k < 0 || S.at(i - k) == '0')
      {
        for (int j = 0; j <= i; j++)
        {
          tmp += dp[j];
        }
      }
      else
      {
        for (int j = i - k + 1; j <= i; j++)
        {
          tmp += dp[j];
        }
      }
      dp[i + 1] = tmp % mint::mod();
    }
    ans += (mint(2).pow(N - 1) - dp[N]) * mint(2).pow(k);
  }
  cout << ans.val() << endl;
}