mod = 998244353
n = int(input())
a = [*map(int, input().split())]
ans = 0
for i, v in enumerate(a):
    if i == 0:
        res = pow(2, n - 2, mod)
    elif i < n - 1:
        res = ((i + 2) * pow(2, n - 3, mod)) % mod
    else:
        res = ((n + 1) * pow(2, n - 2, mod)) % mod
    ans = (ans + res * v) % mod
print(ans)