#!/usr/bin/python
# -*- coding: utf-8 -*-

# import
from sys import stdin, setrecursionlimit
setrecursionlimit(10**8)

def int_map():
    return map(int,input().split())

def int_list():
    return list(map(int,input().split()))

def int_mtx(N):
    x = [list(map(int, stdin.readline().split())) for _ in range(N)]
    return x

def str_mtx(N):
    x = [list(stdin.readline()[:-1]) for _ in range(N)]
    return x

def print_space(l):
    return print(" ".join([str(x) for x in l]))



"""    main code    """

N = int(input())
a = int_list()

MOD = 998244353

ans = 0
for i in range(N):
    ans += a[i]*pow(2,i,MOD)*(pow(2,N-(i+1),MOD)-1)
    ans %= MOD
    ans -= a[i]*(pow(2,i,MOD)-1)*pow(2,N-(i+1),MOD)
    ans %= MOD

print(ans)