N = int(input())
A = [0]+list(map(int,input().split()))
MOD = 998244353
ans = 0
for i in range(1,N):
    ans = (ans+(pow(2,N-i,MOD)-1)*pow(2,i-1,MOD)*A[i])%MOD
for j in range(2,N+1):
    ans = (ans-(pow(2,j-1,MOD)-1)*pow(2,N-j,MOD)*A[j])%MOD
print(ans)