import sys
input=sys.stdin.readline

N=int(input())
A=[0]+list(map(int,input().split()))
Mod=998244353

if N==1:
    print(A[1]%Mod)
    exit(0)

X=0
for i,a in enumerate(A[1:],1):
    X+=(i+1)*a
    X%=Mod

alpha=pow(2,N-2,Mod)
X=(X*alpha)%Mod
print(X)