mod = 998244353
n = int(input())
a = [*map(int, input().split())]
ans = 0
if n == 1:
    ans = a[0]
else:
    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)