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 a = NList;
        var mod = 998_244_353;
        var dp = new long[n][];
        for (var i = 0; i < dp.Length; ++i)
        {
            dp[i] = new long[100001];
            if (i == 0) for (var j = a[i]; j < dp[i].Length; ++j) dp[i][j] = 1;
            else
            {
                for (var j = a[i]; j < dp[i].Length; ++j)
                {
                    var min = a[i - 1];
                    var max = Math.Min(j, Math.Max(0, j - a[i] + a[i - 1]));
                    if (min == 0) dp[i][j] = dp[i - 1][max];
                    else dp[i][j] = (dp[i - 1][max] - dp[i - 1][min - 1] + mod) % mod;
                }
            }
            for (var j = 1; j < dp[i].Length; ++j) dp[i][j] = (dp[i][j] + dp[i][j - 1]) % mod;
        }
        WriteLine(dp[^1][^1]);
    }
}