import sys
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 63 - 1
mod = 998244353

n = ii()

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

print(ans)