mod = 998244353
n = int(input())
a = list(map(int, input().split()))
if n == 1:
    print(a[0] % mod)
    exit()
ans = 0
k = pow(2, n - 2, mod)
for i in range(n):
    ans += k * (i + 2) * a[i]
print(ans % mod)