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();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var s = ReadLine();
        if (s.All(c => c == '0'))
        {
            WriteLine(0);
            return;
        }
        var ans = 1L;
        var mod = 998_244_353;
        var prev = -1;
        for (var i = 0; i < s.Length; ++i)
        {
            if (s[i] == '1')
            {
                if (prev >= 0) ans = ans * (i - prev + 1) % mod;
                prev = i;
            }
        }
        WriteLine(ans);
    }
}