MOD = 998244353
N = int(input())
A = list(map(int, input().split()))
tmp = pow(2, N - 3, MOD)
ans = 0
if N == 1:
    print(A[0])
    exit()
if N == 1:
    print((2 * (A[0] + A[1])) % MOD)
    exit()
for i in range(N):
    ans += A[i] * (i + 2) * tmp
    ans %= MOD
ans += A[i] * (i + 2) * tmp
ans %= MOD
print(ans)