#include #include typedef long long int ll; typedef long double ld; using namespace std; using namespace atcoder; #define inf 1010000000 #define llinf 1001000000000000000ll #define pi 3.14159265358979 #define rep(i, n) for(ll i = 0; i < (n); i++) #define rep1(i, n) for(ll i = 1; i <= (n); i++) #define rep2(i,l,r) for(ll i = (l); i < (r); i++) #define rng(a) a.begin(),a.end() #define fi first #define se second #define pb push_back #define eb emplace_back #define pob pop_back #define mp make_pair #define st string #define sz(x) (int)(x).size() #define mems(x) memset(x, -1, sizeof(x)); #define pcnt __builtin_popcountll #define _GLIBCXX_DEBUG #define dame { puts("-1"); return 0;} #define yes { puts("Yes"); return 0;} #define no { puts("No"); return 0;} #define ret(x) { cout<<(x)< inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; } // srand((unsigned)time(NULL)); rand()を用いる際にmainの頭に置く // clock()/CLOCKS_PER_SEC 秒数を知りたいときに用いる #define mod 998244353 #define mod2 1000000007 //問題に応じて使う方を決める using mint = modint998244353; // .val()で出力 using pl = pair; using ppl = pair; using V = vector; using Graph = vector>; //llをEdgeにする等,適宜書き換える // G.assign(n, vector()); グローバル変数にGを置く時に置く int main() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); ll n; cin >> n; ll a[n]; rep(i,n) cin >> a[i]; ll t[n+1]; t[0] = 1; rep(i,n){ t[i+1] = t[i]*2; t[i+1]%=mod; } mint ans = 0; rep(i,n){ ans += a[i] * t[n-i-1]; ans -= a[i] * t[i]; } ret(ans.val()); }