import sys
input = sys.stdin.readline
from collections import *

N = int(input())
A = list(map(int, input().split()))
ans = 0
acc = 0
MOD = 998244353

for i in range(N):
    r = pow(2, N-1-i, MOD)
    add = (acc-A[i]*(pow(2, i, MOD)-1))*r%MOD
    ans += add
    ans %= MOD
    acc += pow(2, i)*A[i]
    acc %= MOD

print(ans)