mod = 998244353
n = int(input())
ans = 0
sm_i = 0
cnt = 1
for i, x in enumerate(map(int, input().split())):
    c = cnt
    s = sm_i + cnt
    if i == n - 1:
        ans = (ans + s * x) % mod
    else:
        ans = (ans + s * x * pow(2, n - 2 - i, mod)) % mod
        cnt = (c + cnt) % mod
        sm_i = (sm_i + s) % mod
print(ans)