#include "bits/stdc++.h" using namespace std; #ifdef _DEBUG #define _GLIBCXX_DEBUG #include "dump.hpp" #else #define dump(...) #endif #define int long long #define ll long long #define ll1 1ll #define ONE 1ll #define DBG 1 #define rep(i, a, b) for (int i = (a); i < (b); i++) #define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--) #define loop(n) rep(loop, (0), (n)) #define all(c) begin(c), end(c) const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f; const int MOD = (int)(1e9) + 7; const double PI = acos(-1); const double EPS = 1e-9; #define fi first #define se second #define pb push_back #define eb emplace_back using pii = pair; // template ostream &operator<<(ostream &os,T &t){dump(t);return os;} template istream &operator>>(istream &is, pair &p) { is >> p.first >> p.second; return is; } template ostream &operator<<(ostream &os, pair &p) { os << p.first << " " << p.second; return os; } template void printvv(const vector> &v) { cerr << endl; rep(i, 0, v.size()) rep(j, 0, v[i].size()) { if (typeid(v[i][j]).name() == typeid(INF).name() and v[i][j] == INF) { cerr << "INF"; } else cerr << v[i][j]; cerr << (j == v[i].size() - 1 ? '\n' : ' '); } cerr << endl; } /* typedef __int128_t Int; std::ostream &operator<<(std::ostream &dest, __int128_t value) { std::ostream::sentry s(dest); if (s) { __uint128_t tmp = value < 0 ? -value : value; char buffer[128]; char *d = std::end(buffer); do { --d; *d = "0123456789"[tmp % 10]; tmp /= 10; } while (tmp != 0); if (value < 0) { --d; *d = '-'; } int len = std::end(buffer) - d; if (dest.rdbuf()->sputn(d, len) != len) { dest.setstate(std::ios_base::badbit); } } return dest; } __int128 parse(string &s) { __int128 ret = 0; for (int i = 0; i < s.length(); i++) if ('0' <= s[i] && s[i] <= '9') ret = 10 * ret + s[i] - '0'; return ret; } */ #ifndef _DEBUG #define printvv(...) #endif void YES(bool f) { cout << (f ? "YES" : "NO") << endl; } void Yes(bool f) { cout << (f ? "Yes" : "No") << endl; } template bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; } template struct ModInt { static const int Mod = MOD; unsigned x; ModInt() : x(0) {} ModInt(signed sig) { int sigt = sig % MOD; if (sigt < 0) sigt += MOD; x = sigt; } ModInt(signed long long sig) { int sigt = sig % MOD; if (sigt < 0) sigt += MOD; x = sigt; } int get() const { return (int)x; } ModInt &operator+=(ModInt that) { if ((x += that.x) >= MOD) x -= MOD; return *this; } ModInt &operator-=(ModInt that) { if ((x += MOD - that.x) >= MOD) x -= MOD; return *this; } ModInt &operator*=(ModInt that) { x = (unsigned long long)x * that.x % MOD; return *this; } ModInt &operator/=(ModInt that) { return *this *= that.inverse(); } ModInt operator+(ModInt that) const { return ModInt(*this) += that; } ModInt operator-(ModInt that) const { return ModInt(*this) -= that; } ModInt operator*(ModInt that) const { return ModInt(*this) *= that; } ModInt operator/(ModInt that) const { return ModInt(*this) /= that; } ModInt inverse() const { signed a = x, b = MOD, u = 1, v = 0; while (b) { signed t = a / b; a -= t * b; std::swap(a, b); u -= t * v; std::swap(u, v); } if (u < 0) u += MOD; ModInt res; res.x = (unsigned)u; return res; } }; template ostream &operator<<(ostream &os, const ModInt &m) { return os << m.x; } template istream &operator>>(istream &is, ModInt &m) { signed long long s; is >> s; m = ModInt(s); return is; }; // pow(mint(2), 1000) のように template ModInt pow(ModInt a, unsigned long long k) { ModInt r = 1; while (k) { if (k & 1) r *= a; a *= a; k >>= 1; } return r; } //#define int long long を使っても大丈夫 using mint = ModInt<1000000007>; // nCrで用いる vector fact, factinv; // nCrで用いる 予め計算しておく void nCr_compute_factinv(int N) { N = min(N, mint::Mod - 1); fact.resize(N + 1); factinv.resize(N + 1); fact[0] = 1; rep(i, 1, N + 1) fact[i] = fact[i - 1] * i; factinv[N] = fact[N].inverse(); for (int i = N; i >= 1; i--) factinv[i - 1] = factinv[i] * i; } mint nCr(int n, int r) { if (n >= mint::Mod) return nCr(n % mint::Mod, r % mint::Mod) * nCr(n / mint::Mod, r / mint::Mod); return r > n ? 0 : fact[n] * factinv[n - r] * factinv[r]; } mint nHr(int n, int r) { return r == 0 ? 1 : nCr(n + r - 1, r); } signed main(signed argc, char *argv[]) { cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(12); int N; cin >> N; vectora(N); rep(i, 0, N) { cin >> a[i]; } nCr_compute_factinv(N + 10); mint ans = 0; rep(i, 0, N) { ans += nCr(N - 1, i)*a[i]; } cout << ans << endl; return 0; }