p = 998244353


def Compute_Factorials(mx=10**6):
    global p
    fac = [1] + [0] * mx
    inv = [0] + [0] * mx
    fac_inv = [1] + [0] * mx
    for i in range(1, mx + 1):
        fac[i] = fac[i - 1] * i % p
        if i == 1:
            inv[i] = 1
        else:
            "We have p = (p // i) * i + r."
            inv[i] = -inv[p % i] * (p // i) % p
        fac_inv[i] = fac_inv[i - 1] * inv[i] % p
    return fac, inv, fac_inv


fac, inv, fac_inv = Compute_Factorials()


def binom(n, r):
    global p
    if 0 <= r <= n:
        return fac[n] * (fac_inv[r] * fac_inv[n - r] % p) % p
    else:
        return 0


def perm(n, r):
    global p
    if 0 <= r <= n:
        return fac[n] * fac_inv[n - r] % p
    else:
        return 0


N = int(input())
A = list(map(int, input().split()))
cum = [0] * 2
for i, a in enumerate(A):
    if N - i - 2 >= 0:
        cum.append(a * pow(2, N - i - 2, p) % p)
    else:
        cum.append(a)
for i in range(N + 1):
    cum[i + 1] += cum[i]
ans = cum[N + 1] % p
for x in range(1, N):
    cand = ((x - 1) * pow(2, x - 2, p) + pow(2, x, p)) % p
    coef = cum[N + 1] - cum[x + 1]
    # print(cand, coef)
    ans += cand * coef % p
    ans %= p
print(ans)