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

mod = 998244353

if n == 1:
    print(A[0]%mod)
    exit()

ans = 0
for i, a in enumerate(A):
    ans += (i+2)*a
    ans %= mod
ans *= pow(2, n-2, mod)
ans %= mod
print(ans)