#include #include #include #include #include #include #include using namespace std; using ll = long long; constexpr int P = 1000000007; ll powmod(ll n, ll k) { ll r = 1, t = n % P; for (; k != 0; k /= 2) { if (k & 1) r = r * t % P; t = t * t % P; } return r; } ll inv(ll n) { return powmod(n, P - 2); } vector f0, f1; void init(int n) { f0.resize(n + 1); f0[0] = 1; for (int i = 1; i <= n; i++) { f0[i] = (ll)f0[i - 1] * i % P; } f1.resize(n + 1); f1[n] = inv(f0[n]); for (int i = n; i > 0; i--) { f1[i - 1] = (ll)f1[i] * i % P; } } ll fact(int k) { return f0[k]; } ll comb(int n, int k) { if (n < k || k < 0) return 0; return (ll)f0[n] * f1[k] % P * f1[n - k] % P; } int main() { ios::sync_with_stdio(false); cin.tie(0); int n; cin >> n; init(n); ll s = 0; for (int i = 0; i < n; i++) { ll a; cin >> a; s += a * comb(n - 1, i) % P; } cout << s << endl; return 0; }