#include<bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
using ll=long long;
using ld=long double;
using ull=unsigned long long;
using i128 = __int128_t;
#define rep(i,n) for(ll i=0;i<ll(n);i++)
#define rep2(i,n) for(ll i=n-1;i>=0;i--)
#define rep3(i,a,b) for(ll i=a;i<=ll(b);i++)
#define rep4(i,a,b) for(ll i=a;i>=ll(b);i--)
#define forv(i,V) for(const auto& i:V)
#define all(x) x.begin(),x.end()
#define fi first
#define se second
#define SIZE(x) int(x.size())
//constexpr ll mod=998244353;
//constexpr ll mod=1000000007;
#define pi 3.14159265358979323
#define INF32 2147483647
#define INF64 9223372036854775807
#define faster ios::sync_with_stdio(false);std::cin.tie(nullptr)
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define rev reverse
#define vi vector<int>
#define vll vector<ll>
#define vpi vector<pair<int,int>>
#define vpll vector<pair<ll,ll>>
#define vvi vector<vector<int>>
#define vvll vector<vector<ll>>
#define prq priority_queue
#define lb lower_bound
#define ub upper_bound
#define popcnt __builtin_popcountll
#define TLE while(true)
#define RE assert(false);
#define MLE vector<vector<vector<long long>>> mle_mle(400,vector<vector<long long>>(1000,vector<long long>(1000)));
const string YESNO[2] = {"NO", "YES"};
const string YesNo[2] = {"No", "Yes"};
const string yesno[2] = {"no", "yes"};
#define rall(n) (n).rbegin(),(n).rend()
#define INT(...) int __VA_ARGS__;scan(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;scan(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;scan(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;scan(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;scan(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__;scan(__VA_ARGS__)
template<typename T,typename U>
ostream &operator<<(ostream&os,const pair<T,U>&p){os<<p.first<<" "<<p.second;return os;}
template<typename T,typename U>
istream &operator>>(istream&is,pair<T,U>&p){is>>p.first>>p.second;return is;}
template<typename T>
ostream &operator<<(ostream&os,const vector<T>&v){for(auto it=v.begin();it!=v.end();){os<<*it<<((++it)!=v.end()?" ":"");}return os;}
template<typename T>
istream &operator>>(istream&is,vector<T>&v){for(T &in:v){is>>in;}return is;}
void scan(){}
template<class Head,class... Tail>
void scan(Head&head,Tail&... tail){cin>>head;scan(tail...);}
template<class T>
void print(const T &t){cout<<t<<'\n';}
template<class Head, class... Tail>
void print(const Head &head, const Tail &... tail){cout<<head<<' ';print(tail...);}
template<class... T>
void fin(const T &... a){print(a...);exit(0);}
ll max(int a,ll b){return max((ll)a,b);}
ll max(ll a,int b){return max((ll)b,a);}
ll min(int a,ll b){return min((ll)a,b);}
ll min(ll a,int b){return min((ll)b,a);}
//a以上b以下の個数
template<typename T>
ll RangeOK(ll a,ll b,vector<T> &v){
  return max(ub(all(v),b)-lb(all(v),a),0);
}
template <typename T>
vector<T> compress(vector<T> &X) {
    vector<T> vals = X;
    sort(vals.begin(), vals.end());
    vals.erase(unique(vals.begin(), vals.end()), vals.end());
    for (int i = 0; i < (int)X.size(); i++) {
        X[i] = lower_bound(vals.begin(), vals.end(), X[i]) - vals.begin();
    }
    return vals;
}
//setprecision(20)
namespace yakisoba{
    struct dsu{
        dsu() : _n(0) {}
        dsu(int n) : _n(n), parent(n, -1), groupsize(n) {}
        int merge(int a,int b){
            if(a<0||a>=_n||b<0||b>=_n) cerr<<"UnionFind Range out:"<<a<<" "<<b<<endl;
            int x=leader(a);
            int y=leader(b);
            if(x==y) return x;
            groupsize--;
            if(parent[x]>parent[y]) swap(x,y);
            parent[x]+=parent[y];
            parent[y]=x;
            return x;
        }
        bool same(int a,int b){
            if(a<0||a>=_n||b<0||b>=_n) cerr<<"UnionFind Range out:"<<a<<" "<<b<<endl;
            if(leader(a)==leader(b)) return true;
            else return false;
        }
        int leader(int a){
            if(a<0||a>=_n) cerr<<"UnionFind Range out:"<<a<<endl;
            if(parent[a]<0) return a;
            parent[a]=leader(parent[a]);
            return parent[a];
        }
        int size(int a){
            if(a<0||a>=_n) cerr<<"UnionFind Range out:"<<a<<endl;
            return -parent[leader(a)];
        }
        vector<vector<int>> groups(){
            vector<int> group_size(_n),leader_list(_n);
            for(int i=0;i<_n;i++){
                leader_list[i]=leader(i);
                group_size[leader_list[i]]++;
            }
            vector<vector<int>> ans(_n);
            for(int i=0;i<_n;i++){
                ans[i].reserve(group_size[i]);
            }
            for(int i=0;i<_n;i++){
                ans[leader_list[i]].push_back(i);
            }
            ans.erase(remove_if(ans.begin(),ans.end(),[&](const vector<int>& v){return v.empty();}),ans.end());
            return ans;
        }
        public:
            int groupsize;
        private:
            //代表元はそのグループの要素数を符号を反転させて持つ
            //それ以外は親を持つ
            int _n;
            vector<int> parent;
    };
}
using namespace yakisoba;
struct Barrett {
  using u32=unsigned int;
  using i64=long long;
  using u64=unsigned long long;
  u32 m;
  u64 im;
  Barrett():m(),im(){}
  Barrett(int n):m(n),im(u64(-1)/m+1){}
  constexpr inline i64 quo(u64 n){
    u64 x=u64((__uint128_t(n)*im)>>64);
    u32 r=n-x*m;
    return m<=r?x-1:x;
  }
  constexpr inline i64 rem(u64 n){
    u64 x=u64((__uint128_t(n)*im)>>64);
    u32 r=n-x*m;
    return m<=r?r+m:r;
  }
  constexpr inline pair<i64,int> quorem(u64 n){
    u64 x=u64((__uint128_t(n)*im)>>64);
    u32 r=n-x*m;
    if(m<=r)return{x-1,r+m};
    return{x,r};
  }
  constexpr inline i64 pow(u64 n,i64 p){
    u32 a=rem(n),r=m==1?0:1;
    while(p){
      if(p&1)r=rem(u64(r)*a);
      a=rem(u64(a)*a);
      p>>=1;
    }
    return r;
  }
};
struct Amint{
  int get() const {return x;}
  inline unsigned int rem(unsigned long long p){return barrett().rem(p);}
  static inline Barrett &barrett(){
    static Barrett b;
    return b;
  }
  static inline int &get_mod(){
    static int modp = 0;
    return modp;
  }
  static void set_mod(int md){
    assert(0<md&&md<=(1LL<<30)-1);
    get_mod()=md;
    barrett()=Barrett(md);
  }
  int x;
  Amint():x(0){}
  Amint(int64_t y){
    int z=y%get_mod();
    if(z<0) z+=get_mod();
    x=z;
  }
  Amint &operator+=(const Amint &p){
    if((x+=p.x)>=get_mod())x-=get_mod();
    return *this;
  }
  Amint &operator-=(const Amint &p){
    if((x+=get_mod()-p.x)>=get_mod())x-=get_mod();
    return *this;
  }
  Amint &operator*=(const Amint &p){
    x=rem((unsigned long long)x*p.x);
    return *this;
  }
  Amint &operator/=(const Amint &p){
    *this *=p.inv();
    return *this;
  }
  Amint &operator++(){
    if(++x==get_mod()) x=0;
    return *this;
  }
  Amint &operator--(){
    if(x--==0) x=get_mod()-1;
    return *this;
  }
  Amint operator-() const{return Amint(-x);}
  Amint operator+(const Amint &p) const{
    return Amint(*this)+=p;
  }
  Amint operator-(const Amint &p) const{
    return Amint(*this)-=p;
  }
  Amint operator*(const Amint &p) const{
    return Amint(*this)*= p;
  }
  Amint operator/(const Amint &p) const{
    return Amint(*this)/= p;
  }
  bool operator==(const Amint &p) const {return x==p.x;}
  bool operator!=(const Amint &p) const {return x!=p.x;}
  bool operator<(const Amint &p) const {return x<p.x;}
  bool operator>(const Amint &p) const {return x>p.x;}
  bool operator<=(const Amint &p) const {return x<=p.x;}
  bool operator>=(const Amint &p) const {return x>=p.x;}
  Amint pow(int64_t n) const{
    Amint r(1),m(x);
    while(n>0){
      if (n&1) r*=m;
      m*=m;
      n>>=1;
    }
    return r;
  }
  Amint inv() const{
    int a=x,b=get_mod(),u=1,v=0,t;
    while(b>0){
      t=a/b;
      swap(a-=t*b,b);
      swap(u-=t*v,v);
    }
    return Amint(u);
  }
  friend ostream &operator<<(ostream &os,const Amint &p){
    return os<<p.x;
  }
  friend istream &operator>>(istream &is,Amint &a){
    int64_t t;
    is>>t;
    a=Amint(t);
    return(is);
  }
};
template<int modp>
struct modint{
  int get() const{return x;}
  static constexpr int get_mod(){return modp;}
  int x;
  modint():x(0){}
  modint(int64_t y):x(y>=0?y%modp:(modp-(-y)%modp)%modp){}
  modint &operator+=(const modint &p){
    if((x+=p.x)>=modp)x-=modp;
    return *this;
  }
  modint &operator-=(const modint &p){
    if((x+=modp-p.x)>=modp)x-=modp;
    return *this;
  }
  modint &operator*=(const modint &p){
    x=(int)(1LL*x*p.x%modp);
    return *this;
  }
  modint &operator/=(const modint &p){
    *this*=p.inverse();
    return *this;
  }
  modint operator-() const{return modint(-x);}
  modint operator+(const modint &p) const{
    return modint(*this)+=p;
  }
  modint operator-(const modint &p) const{
    return modint(*this)-=p;
  }
  modint operator*(const modint &p) const{
    return modint(*this)*= p;
  }
  modint operator/(const modint &p) const{
    return modint(*this)/= p;
  }
  modint &operator++(){
    if(++x==get_mod()) x=0;
    return *this;
  }
  modint &operator--(){
    if(x--==0) x=get_mod()-1;
    return *this;
  }
  bool operator==(const modint &p) const {return x==p.x;}
  bool operator!=(const modint &p) const {return x!=p.x;}
  bool operator<(const modint &p) const {return x<p.x;}
  bool operator>(const modint &p) const {return x>p.x;}
  bool operator<=(const modint &p) const {return x<=p.x;}
  bool operator>=(const modint &p) const {return x>=p.x;}
  modint pow(int64_t n) const{
    modint r(1),m(x);
    while(n>0){
      if (n&1) r*=m;
      m*=m;
      n>>=1;
    }
    return r;
  }
  modint inv()const{
    int a=x,b=get_mod(),u=1,v=0,t;
    while(b>0){
      t=a/b;
      swap(a-=t*b,b);
      swap(u-=t*v,v);
    }
    return modint(u);
  }
  friend ostream &operator<<(ostream &os,const modint &p){
    return os<<p.x;
  }
  friend istream &operator>>(istream &is,modint &a){
    int64_t t;
    is>>t;
    a=modint(t);
    return(is);
  }
};
#define mint Amint
//#define MOD Amint::set_mod(1000000007);
#define MOD Amint::set_mod(998244353);
//#define mint modint
//modが不変の場合は上3つを利用
//modが10^9+7と998244353の時は, MOD; を最初に実行する
//modが可変の場合は1番下を利用 mint<998244353>のように宣言
long long pow(long long n,long long k){
    long long ans=1;
    while(k){
        if(k&1) ans*=n;
        n*=n;
        k>>=1;
    }
    return ans;
}
//modをとらない場合の累乗 modをとる場合はa.pow(1000)のようにmodintを使う
mint comb_naive(mint n,mint k){
    if(k<0||n<k) return 0;
    k=min(k,n-k);
    mint a=1,b=1;
    for(mint i=1;i<=k;++i){
        a*=i;
        b*=n-i+1;
    }
    return a.inv()*b;
}
#define k_max 1000000
vector<mint> fac(k_max);
vector<mint> inv_fac(k_max);
void set_comb(){
  MOD;
  fac[0]=1;
  for(mint i=1;i<k_max;++i){
    fac[i.get()]=fac[i.get()-1]*i;
  }
  inv_fac[k_max-1]=fac[k_max-1].inv();
  inv_fac[0]=1;
  for(mint i=k_max-2;i>=1;--i){
    inv_fac[i.get()]=inv_fac[i.get()+1]*(i+1);
  }
}
mint comb(mint n,mint k){
  if(k<0||n<k) return 0;
  return fac[n.get()]*inv_fac[k.get()]*inv_fac[(n-k).get()];
}
int main(){
  set_comb();
  LL(n);
  vector<mint> v(n);
  scan(v);
  mint ans=0;
  rep(i,n){
    ans+=v[i]*(mint(2).pow(n-i-1)-1);
    ans-=v[i]*(mint(2).pow(i)-1);
  }
  fin(ans);
}