#include <iostream>
#include <vector>

using namespace std;

const int MOD = 998244353;

int main(){
    const int maxSize = 500001;
    vector<long long> inv(maxSize);
    vector<long long> fact(maxSize);
    vector<long long> factInv(maxSize);
    for(int i=0;i<2;i++) inv[i] = fact[i] = factInv[i] = 1;
    for(int i=2;i<maxSize;i++){
        inv[i] = inv[MOD % i] * (MOD - MOD / i) % MOD;
        fact[i] = fact[i-1] * i % MOD;
        factInv[i] = factInv[i-1] * inv[i] % MOD;
    }
    auto comb = [&](int n, int r){
        if(n < r || r < 0) return 0LL;
        return fact[n] * factInv[n-r] % MOD * factInv[r] % MOD;
    };
    int N; cin >> N;
    long long res = 0;
    for(int i=0;i<N;i++){
        long long a; cin >> a;
        res += a * (i+2) % MOD;
        res %= MOD;
    }
    for(int i=0;i<N-2;i++) res = 2*res%MOD;
    cout << res << endl;
}