/* -*- coding: utf-8 -*-
 *
 * 1325.cc:  No.1325 Subsequence Score - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 500000;
const int MOD = 998244353;

/* typedef */

typedef long long ll;

/* global variables */

int as[MAX_N];

/* subroutines */

int powmod(int a, int n) {  // a^n % MOD
  int pm = 1;
  while (n > 0) {
    if (n & 1) pm = (ll)pm * a % MOD;
    a = (ll)a * a % MOD;
    n >>= 1;
  }
  return pm;
}

/* main */

int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", as + i);

  if (n == 1) printf("%d\n", as[0] % MOD);
  else {
    int sum = 0;
    for (int i = 0; i < n; i++)
      sum = (sum + (ll)(i + 2) * as[i] % MOD) % MOD;

    int ans = (ll)sum * powmod(2, n - 2) % MOD;
    printf("%d\n", ans);
  }
  return 0;
}