import sys

input = sys.stdin.buffer.readline
mod = 998244353
n = int(input())
A = list(map(int, input().split()))

pow2 = [1] * (n + 1)
for i in range(n):
    pow2[i + 1] = 2 * pow2[i] % mod

ans = 0
for i in range(n):
    left = i
    right = n - i - 1
    ans += pow2[left] * A[i] % mod
    ans %= mod
    ans += (pow2[right + 1] - 1) * A[i] % mod
    ans %= mod
    ans -= pow2[right] * A[i] % mod
    ans %= mod
    ans -= (pow2[left + 1] - 1) * A[i] % mod
    ans %= mod
print(ans)