MOD = 998244353
N = int(input())
A = list(map(int, input().split()))
ans = 0
tmp1 = 0
tmp2 = 0
suma = 0
mp = 1
for a in reversed(A):
    tmp2 += tmp1 + tmp2
    tmp2 %= MOD
    suma += a
    tmp1 = suma * mp
    tmp1 %= MOD
    ans = tmp1 + tmp2
    ans %= MOD
    mp *= 2
    mp %= MOD
print(ans)