#include <bits/stdc++.h>
// clang-format off
using namespace std; using ll=long long; using ull=unsigned long long; using pll=pair<ll,ll>; const ll INF=4e18;
void print0(){}; template<typename H,typename... T> void print0(H h,T... t){cout<<h;print0(t...);}
void print(){print0("\n");}; template<typename H,typename... T>void print(H h,T... t){print0(h);if(sizeof...(T)>0)print0(" ");print(t...);}
void perr0(){}; template<typename H,typename... T> void perr0(H h,T... t){cerr<<h;perr0(t...);}
void perr(){perr0("\n");}; template<typename H,typename... T>void perr(H h,T... t){perr0(h);if(sizeof...(T)>0)perr0(" ");perr(t...);}
void ioinit() { cout<<fixed<<setprecision(15); cerr<<fixed<<setprecision(6); ios_base::sync_with_stdio(0); cin.tie(0); }
#define debug1(a) { cerr<<#a<<":"<<a<<endl; }
#define debug2(a,b) { cerr<<#a<<":"<<a<<" "<<#b<<":"<<b<<endl; }
#define debug3(a,b,c) { cerr<<#a<<":"<<a<<" "<<#b<<":"<<b<<" "<<#c<<":"<<c<<endl; }
#define debug4(a,b,c,d) { cerr<<#a<<":"<<a<<" "<<#b<<":"<<b<<" "<<#c<<":"<<c<<" "<<#d<<":"<<d<<endl; }
// clang-format on

const ll MODULO = 998244353;
ll rangesum(ll l, ll r, vector<ll>& cum) {
    if (l == 0) return cum[r];
    return cum[r] - cum[l - 1];
}
int main() {
    // 一番左、一番右として選ばれる回数
    ioinit();
    ll N;
    cin >> N;
    vector<ll> A(N);
    for (ll i = 0; i < N; i++) {
        cin >> A[i];
    }
    vector<ll> cum(N, A[0]);
    for (ll i = 1; i < N; i++) {
        cum[i] = A[i] + cum[i - 1];
    }
    vector<ll> pow2(N + 1, 1);
    for (ll i = 1; i <= N; i++) {
        pow2[i] = pow2[i - 1] * 2 % MODULO;
    }
    ll ans = 0;
    for (ll i = 0; i < N; i++) {
        ll left = pow2[N - i - 1] - 1;
        ll right = pow2[i] - 1;
        ans += (left - right) * A[i] % MODULO;
    }
    ans %= MODULO;
    if (ans < 0) ans += MODULO;
    print(ans);

    return 0;
}