#include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define rep(i, n) for(int(i) = 0; (i) < (n); (i)++) #define FOR(i, m, n) for(int(i) = (m); (i) < (n); (i)++) #define All(v) (v).begin(), (v).end() #define pb push_back #define MP(a, b) make_pair((a), (b)) using ll = long long; using pii = pair; using pll = pair; const int INF = 1 << 30; const ll LINF = 1LL << 60; const int MOD = 1e9 + 7; template class ModInt { using u64 = uint_fast64_t; public: u64 val; ModInt(const u64 x = 0) : val(x % MOD) {} constexpr u64 &value() { return val; } constexpr ModInt operator-() { return val ? MOD - val : 0; } constexpr ModInt operator+(const ModInt &rhs) const { return ModInt(*this) += rhs; } constexpr ModInt operator-(const ModInt &rhs) const { return ModInt(*this) -= rhs; } constexpr ModInt operator*(const ModInt &rhs) const { return ModInt(*this) *= rhs; } constexpr ModInt operator/(const ModInt &rhs) const { return ModInt(*this) /= rhs; } constexpr ModInt &operator+=(const ModInt &rhs) { val += rhs.val; if(val >= MOD) { val -= MOD; } return *this; } constexpr ModInt &operator-=(const ModInt &rhs) { if(val < rhs.val) { val += MOD; } val -= rhs.val; return *this; } constexpr ModInt &operator*=(const ModInt &rhs) { val = val * rhs.val % MOD; return *this; } constexpr ModInt &operator/=(const ModInt &rhs) { *this *= rhs.inv(); return *this; } constexpr bool operator==(const ModInt &rhs) { return this->a == rhs.a; } constexpr bool operator!=(const ModInt &rhs) { return this->a != rhs.a; } friend constexpr ostream &operator<<(ostream &os, const ModInt &x) { return os << x.val; } friend constexpr istream &operator>>(istream &is, ModInt &x) { return is >> x.val; } constexpr ModInt inv() const { u64 x = val, y = MOD, u = 1, v = 0, t = 0; while(y > 0) { t = x / y; x -= t * y; swap(x, y); u -= t * v; swap(u, v); } return ModInt(u); } constexpr ModInt pow(int e) const { u64 x = 1, p = val; while(e > 0) { if(e % 2 == 0) { p = (p * p) % MOD; e /= 2; } else { x = (x * p) % MOD; e--; } } return ModInt(x); } }; //二項係数(nCk mod.p;1<=k<=n<=1e7,pは素数)for ModInt template struct BiCoefficient { vector fac, finv, inv; BiCoefficient(const int MAX) : fac(MAX), finv(MAX), inv(MAX) { 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; inv[i] = -inv[MOD % i] * (MOD / i); finv[i] = finv[i - 1] * inv[i]; } } T comb(int n, int k) { if(n < k) return 0; if(n < 0 || k < 0) return 0; return fac[n] * finv[k] * finv[n - k]; } }; using mint = ModInt; int main() { int N; cin >> N; vector A(N); rep(i, N) cin >> A[i]; BiCoefficient Bicoef(200); mint res = 0; rep(i, N) { res += Bicoef.comb(N - 1, i) * mint(A[i]); } cout << res << endl; return 0; }