#include #include using namespace std; const int mod = 1000000007; //B template struct ModInt{ int n; ModInt():n(0){} ModInt(int n_):n(n_ >= 0 ? n_%mod : mod - ((-n_)%mod) ){} ModInt &operator+=(const ModInt &p){ if((n+=p.n) >= mod)n-=mod; return *this; } ModInt &operator-=(const ModInt &p){ n+=mod-p.n; if(n >= mod)n-=mod; return *this; } ModInt &operator*=(const ModInt &p){ n = (int) ((1LL*n*p.n)%mod); return *this; } ModInt &operator/=(const ModInt &p){ *this *= p.inverse(); return *this; } ModInt operator-() const {return ModInt(-n);} 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 n==p.n;} bool operator!=(const ModInt &p) const {return n!=p.n;} ModInt inverse() const { int a = n,b = mod,u = 1,v = 0; while(b){ int t = a/b; a -= t*b; swap(a,b); u -= t*v; swap(u,v); } return ModInt(u); } ModInt pow(int64_t z) const { ModInt ret(1),mul(n); while(z > 0){ if(z & 1) ret *= mul; mul *= mul; z >>= 1; } return ret; } friend ostream &operator<<(ostream &os, const ModInt &p){ return os << p.n; } friend istream &operator>>(istream &is, ModInt &a){ int64_t t; is >> t; a = ModInt (t); return (is); } }; using mint = ModInt; //E mint table[100000]; int main(){ int n;cin>>n; table[0] = 1; for(int i = 1; n > i; i++){ table[i] = table[i-1]*(n-i)/i; } mint ans = 0; for(int i = 0; n > i; i++){ mint t;cin>>t; ans += t*table[i]; } cout << ans << endl; }