#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i=0;i<(n);i++)
#define per(i,n) for(int i=(n)-1;i>=0;i--)
#define all(x) x.begin(),x.end()
typedef long long ll;
//using mint = modint;
using mint = modint998244353;
//using mint = modint1000000007;
using P = pair<int, int>;

const ll INF=1LL<<60, dx[]={0,1,0,-1},dy[]={1,0,-1,0};
template <typename T> inline bool chmin(T& a,const T&b) {if(a>b){a=b; return 1;} return 0;}
template <typename T> inline bool chmax(T& a,const T&b) {if(a<b){a=b; return 1;} return 0;}

int main(){

    int n;
    cin >> n;

    vector<mint> a(n);
    rep(i,n) {ll t;cin >> t;a[i]=t;}

    mint pow2[200001];
    mint sum_pow2[200002];
    pow2[0]=1;
    sum_pow2[0]=0;
    rep(i,200000) pow2[i+1]=pow2[i]*2;
    rep(i,200001) sum_pow2[i+1]=sum_pow2[i]+pow2[i];

    auto get_pw2=[&](int l,int r) -> mint {
        return sum_pow2[r]-sum_pow2[l];
    };

    mint ans=0;
    for(int i=0;i<n;i++) {
        int l=i,r=n-1-i;

        ans += a[i] * get_pw2(l,r);
    }

    /*
    for(int k=1;k<n;k++) {
        for(int i=0;i<min(n-k,k);i++) {
            int p=(n-1-i)/k;
            int r=i+k*p;
            ans+= (a[i]-a[r])*pow2[n-k-1];
        }
    }
    */
    cout << ans.val() << endl;

    return 0;

}