#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long long ll; typedef uint64_t ull; typedef pair P; typedef pair Pid; typedef pair Pdi; typedef pair Pl; typedef pair Pll; typedef pair> PP; typedef pair PPi; constexpr double PI = 3.1415926535897932; // acos(-1) constexpr double EPS = 1e-9; constexpr int INF = 1001001001; constexpr int mod = 1000000007; // constexpr int mod = 998244353; #define chmax(x, y) x = max(x, y) #define chmin(x, y) x = min(x, y) #define chadd(x, y) x = (x + y) % mod template struct ModInt{ int x; ModInt() : x(0) {} ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} ModInt &operator+=(const ModInt &p){ if((x += p.x) >= mod) x -= mod; return *this; } ModInt &operator-=(const ModInt &p){ if((x += mod - p.x) >= mod) x -= mod; return *this; } ModInt &operator*=(const ModInt &p){ x = (int)(1LL * x * p.x % mod); 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;} bool operator==(const ModInt &p) const {return x == p.x;} bool operator!=(const ModInt &p) const {return x != p.x;} ModInt inverse() const{ int a = x, b = 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); } ModInt pow(int64_t n) const{ ModInt ret(1), mul(x); while(n > 0){ if(n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } 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); } static int get_mod() {return mod;} }; using modint = ModInt; template struct Combination{ int sz; vector fact_; vector ifact_; vector inv_; Combination(int n = 1e+6) : sz(n) { fact_.resize(sz + 1); ifact_.resize(sz + 1); inv_.resize(sz + 1); fact_[0] = ifact_[sz] = inv_[0] = 1; for(int i = 1; i <= sz; ++i) fact_[i] = fact_[i - 1] * i; ifact_[sz] /= fact_[sz]; for(int i = sz; i > 0; --i) ifact_[i - 1] = ifact_[i] * i; for(int i = 1; i <= sz; ++i) inv_[i] = ifact_[i] * fact_[i - 1]; } inline T fact(int k) const {return fact_[k];} inline T ifact(int k) const {return ifact_[k];} inline T inv(int k) const {return inv_[k];} T get_permutation(int n, int k){ if(n < 0 || k < 0 || n < k) return 0; return fact(n) * ifact(n - k); } T get_combination(int n, int k){ if(n < 0 || k < 0 || n < k) return 0; return fact(n) * ifact(k) * ifact(n - k); } }; int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); int n; cin >> n; Combination c(n); modint ans = 0; for(int i = 0; i < n; ++i){ modint a; cin >> a; ans += c.get_combination(n - 1, i) * a; } cout << ans << endl; }