#include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; using ld = long double; using pint = pair; using pll = pair; #define MOD 1000000007LL #define INF 1000000000LL #define EPS 1e-10 #define FOR(i,n,m) for(ll i=n;i<(int)m;i++) #define REP(i,n) FOR(i,0,n) #define DUMP(a) REP(d,a.size()){cout< fact(MAX_N+1, INF); long long mod_fact(long long n, long long& e) { if(fact[0] == INF) { fact[0]=1; if(MAX_N != 0) fact[1]=1; for(ll i = 2; i <= MAX_N; ++i) { fact[i] = (fact[i-1] * i) % MOD; } } e = 0; if(n == 0) return 1; long long res = mod_fact(n / MOD, e); e += n / MOD; if((n / MOD) % 2 != 0) return (res * (MOD - fact[n % MOD])) % MOD; return (res * fact[n % MOD]) % MOD; } // return nCk long long mod_comb(long long n, long long k) { if(n < 0 || k < 0 || n < k) return 0; long long e1, e2, e3; long long a1 = mod_fact(n, e1), a2 = mod_fact(k, e2), a3 = mod_fact(n - k, e3); if(e1 > e2 + e3) return 0; return (a1 * mod_inverse((a2 * a3) % MOD, MOD)) % MOD; } int main() { cin.tie(0); ios::sync_with_stdio(false); ll n; cin >> n; vector a(n); REP(i, n) cin >> a[i]; ll ans = 0; REP(i, n) { ans += a[i] * mod_comb(n - 1, i); ans %= MOD; } cout << ans << endl; return 0; } /* --------------------------------------- */