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 a = NList; var mod = 998_244_353; var ans = 0L; for (var i = 0; i < n; ++i) { if (i + 1 < n) ans = (ans + (long)a[i] * (i + 2) % mod) % mod; else ans = (ans + (long)a[i] * (i + 2) * 2 % mod) % mod; } ans = ans * 499122177 % mod * 499122177 % mod; for (var i = 0; i < n - 1; ++i) ans = ans * 2 % mod; WriteLine(ans); } }