#include using namespace std; template struct mod_int{ int64_t val; constexpr mod_int():val(0){} constexpr mod_int(int64_t x)noexcept:val(x>=0?x%MOD:(MOD-(-x)%MOD)%MOD){} constexpr int64_t value()const noexcept{return val;} constexpr int64_t get_MOD()const noexcept{return MOD;} constexpr mod_int operator+(mod_int const& rhs){ return mod_int(*this)+=rhs; } constexpr mod_int operator-(mod_int const& rhs){ return mod_int(*this)-=rhs; } constexpr mod_int operator*(mod_int const& rhs){ return mod_int(*this)*=rhs; } constexpr mod_int operator/(mod_int const& rhs){ return mod_int(*this)/=rhs; } constexpr mod_int &operator+=(mod_int const& rhs)noexcept{ val += rhs.val; if(val>=MOD)val-=MOD; return *this; } constexpr mod_int &operator-=(mod_int const& rhs)noexcept{ if(val(mod_int const& rhs)const{ return val>rhs.val; } constexpr bool operator<=(mod_int const& rhs)const{ return !(val>rhs.val); } constexpr bool operator>=(mod_int const& rhs)const{ return !(val>(std::istream& is, mod_int & mi){ int64_t t=0;is>>t; mi = mod_int(t); return is; } constexpr mod_int inverse(){ int64_t a=val,b=MOD,u=1,v=0,t=0; while(b>0){ t=a/b; std::swap(a-=t*b,b); std::swap(u-=t*v,v); } return mod_int(u); } constexpr mod_int mpow(int64_t n)const{ mod_int res(1),e(*this); while(n){ if(n&1)res*=e; e*=e; n>>=1; } return res; } }; using mint = mod_int<1000000007>; mint mpow(int64_t p,int64_t n){ mint res=1; mint e = p; while(n){ if(n&1)res*=e; e*=e; n>>=1; } return res; } struct combination{ using i64 = int_fast64_t; static constexpr i64 COM_MAX = 2e6; static constexpr i64 MOD = 1e9+7; vector fac,inv,finv; combination(){ fac.resize(COM_MAX); inv.resize(COM_MAX); finv.resize(COM_MAX); fac[0] = fac[1] = 1; inv[1] = 1; finv[0] = finv[1] = 1; for(int i=2;i mint nCk(T n,T k){ if(n=COM_MAX){ mint res1 = mint(1); mint res2 = mint(fac[k]); for(int i=1;i<=k;++i){ res1 *= n-(i-1); } return res1/res2; } return mint(fac[n]*(finv[k]*finv[n-k]%MOD)); } template mint nHk(T n,T k){ return nCk(n+k-1,k-1); } template mint operator()(T n,T k){ return nCk(n,k); } }; signed main(){ int n; cin>>n; combination com; mint ans; for(int i=1;i<=n;++i){ mint ai; cin>>ai; ans += ai*com(n-1,i-1); } cout<<(ans)<