#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; #define MOD 1000000007 #define INF 1LL << 59 using ld = long double; bool operator<(const pair &a, const pair &b) { if (a.first == b.first) { return b.second > a.second; } return a.first < b.first; } ll a[100010]; const int MAX = 510000; long long fac[MAX], finv[MAX], inv[MAX]; // テーブルを作る前処理 void COMinit() { fac[0] = fac[1] = 1; finv[0] = finv[1] = 1; inv[1] = 1; for (int i = 2; i < MAX; i++) { fac[i] = fac[i - 1] * i % MOD; inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD; finv[i] = finv[i - 1] * inv[i] % MOD; } } // 二項係数計算 long long COM(int n, int k) { if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD; } int main() { std::ios::sync_with_stdio(false); std::cin.tie(0); //cout << fixed << setprecision(5); COMinit(); int N; cin >> N; ll ans = 0; for (int i = 0; i < N; ++i) cin >> a[i]; for (int i = 0; i < N; ++i) { ans += a[i] * COM(N - 1, i); ans %= MOD; } cout << ans << endl; return 0; }