#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <atcoder/modint>

using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(int)(n); i++)

const i64 INF = 1001001001001001001;
using Modint = atcoder::static_modint<998244353>;

int main(){
    int N; cin >> N;
    vector<Modint> A(N);
    rep(i,N){ int a; cin >> a; A[i] = Modint::raw(a); }
    vector<Modint> P2(N+1, Modint(1));
    rep(i,N) P2[i+1] = P2[i] + P2[i];
    Modint ans2[2];
    rep(t,2){
        rep(i,N){
            Modint c = (P2[i] - 1) * P2[N-1-i];
            ans2[t] += c * A[i];
        }
        reverse(A.begin(), A.end());
    }
    Modint ans = ans2[1] - ans2[0];
    cout << ans.val() << '\n';
    return 0;
}


struct ios_do_not_sync{
    ios_do_not_sync(){
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
    }
} ios_do_not_sync_instance;