n=int(input())
a=list(map(int,input().split()))
if n==1:
  print(a[0])
  exit()
M=998244353
two=[1]
for i in range(n):
  two+=[two[-1]*2%M]
c=0
c+=a[0]*two[n-2]
c%=M
for i in range(1,n-1):
  c+=(i*two[i-1]+two[i])*a[i]*two[n-i-1-1]
  c%=M
c+=((n-1)*two[n-1-1]+two[n-1])*a[n-1]
c%=M
print(c)