//header #ifdef LOCAL #include "cxx-prettyprint-master/prettyprint.hpp" #define debug(x) cout << x << endl #else #define debug(...) 42 #endif #pragma GCC optimize("Ofast") #include //types using namespace std; using ll = long long; using ul = unsigned long long; using ld = long double; typedef pair < ll , ll > Pl; typedef pair < int, int > Pi; typedef vector vl; typedef vector vi; template< typename T > using mat = vector< vector< T > >; template< int mod > 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< mod >(t); return (is); } static int get_mod() { return mod; } }; //abreviations #define all(x) (x).begin(), (x).end() #define rall(x) (x).rbegin(), (x).rend() #define rep_(i, a_, b_, a, b, ...) for (int i = (a), max_i = (b); i < max_i; i++) #define rep(i, ...) rep_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__) #define rrep_(i, a_, b_, a, b, ...) for (int i = (b-1), min_i = (a); i >= min_i; i--) #define rrep(i, ...) rrep_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__) #define SZ(x) ((int)(x).size()) #define pb(x) push_back(x) #define eb(x) emplace_back(x) #define mp make_pair #define print(x) cout << x << endl #define vsum(x) accumulate(x, 0LL) #define vmax(a) *max_element(all(a)) #define vmin(a) *min_element(all(a)) #define lb(c, x) distance((c).begin(), lower_bound(all(c), (x))) #define ub(c, x) distance((c).begin(), upper_bound(all(c), (x))) //functions ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; } ll lcm(ll a, ll b) { return a/gcd(a, b)*b;} templatebool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (b T mypow(T x, ll n) { T ret = 1; while(n > 0) { if(n & 1) (ret *= x); (x *= x); n >>= 1; } return ret; } ll modpow(ll x, ll n, const ll mod) { ll ret = 1; while(n > 0) { if(n & 1) (ret *= x); (x *= x); n >>= 1; x%=mod; ret%=mod; } return ret; } uint64_t my_rand(void) { static uint64_t x = 88172645463325252ULL; x = x ^ (x << 13); x = x ^ (x >> 7); return x = x ^ (x << 17); } //graph template template< typename T > struct edge { int src, to; T cost; edge(int to, T cost) : src(-1), to(to), cost(cost) {} edge(int src, int to, T cost) : src(src), to(to), cost(cost) {} edge &operator=(const int &x) { to = x; return *this; } operator int() const { return to; } }; template< typename T > using Edges = vector< edge< T > >; template< typename T > using WeightedGraph = vector< Edges< T > >; using UnWeightedGraph = vector< vector< int > >; //constant //#define inf 1000000005LL #define inf 4000000000000000005LL #define mod 1000000007LL #define endl '\n' typedef modint mint; const long double eps = 0.0001; const long double PI = 3.141592653589793; //library template< typename T > struct Combination { vector< T > _fact, _rfact, _inv; Combination(int sz) : _fact(sz + 1), _rfact(sz + 1), _inv(sz + 1) { _fact[0] = _rfact[sz] = _inv[0] = 1; for(int i = 1; i <= sz; i++) _fact[i] = _fact[i - 1] * i; _rfact[sz] /= _fact[sz]; for(int i = sz - 1; i >= 0; i--) _rfact[i] = _rfact[i + 1] * (i + 1); for(int i = 1; i <= sz; i++) _inv[i] = _rfact[i] * _fact[i - 1]; } inline T fact(int k) const { return _fact[k]; } inline T rfact(int k) const { return _rfact[k]; } inline T inv(int k) const { return _inv[k]; } T P(int n, int r) const { if(r < 0 || n < r) return 0; return fact(n) * rfact(n - r); } T C(int p, int q) const { if(q < 0 || p < q) return 0; return fact(p) * rfact(q) * rfact(p - q); } T H(int n, int r) const { if(n < 0 || r < 0) return (0); return r == 0 ? 1 : C(n + r - 1, r); } }; int main(){ int n; cin>>n; vector a(n); rep(i, n)cin>>a[i]; Combination comb(n); mint ans = 0; rep(i, n){ ans+=comb.C(n-1, i)*a[i]; } print(ans); }