N = int(input())
A = list(map(int, input().split()))

MOD = 998244353
total = 1
two = 1
goal = pow(2, N-2, MOD)
div = pow(2, MOD-2, MOD)
score = 0

for i, a in enumerate(A, start=1):
    score += total * a * goal
    score %= MOD
    if goal != 1:
        goal *= div
        goal %= MOD
    total += two+total
    total %= MOD
    two *= 2
    two %= MOD
print(score)