using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var s = ReadLine();
        var mod = 998_244_353;
        var a = new long[n];
        a[0] = 1;
        for (var i = 1; i < n; ++i) a[i] = a[i - 1] * 2 % mod;
        var dp = new long[n][];
        for (var i = 0; i < n; ++i)
        {
            dp[i] = new long[n];
            if (i == 0)
            {
                dp[i][0] = s[0] - '0';
            }
            else
            {
                for (var j = 0; j <= i; ++j)
                {
                    if (s[i - j] == '0') dp[i][j] = dp[i - 1][j];
                    else dp[i][j] = (a[i - j] + dp[i - 1][j] - (i > j ? dp[i - j - 1][j] : 0) + mod) % mod;
                    if (i + 1 < n) dp[i][j] = (dp[i][j] + dp[i - 1][j]) % mod;
                }
            }
        }
        var ans = 0L;
        for (var j = 0; j < n; ++j) ans = (ans + dp[n - 1][j] * a[j] % mod) % mod;
        WriteLine(ans);
    }
}