#include #define rep(i,n) for(int i=(0);i<(n);i++) using namespace std; typedef long long ll; template bool chmax(T &a, const T &b) { if (a bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; } const ll MOD = 1e9 + 7; const ll max_n = 202020; ll fact[max_n]; bool fact_init = false; ll pow(ll a, ll b){ if(b == 0) return 1; if(b % 2 == 1) return a * pow(a, b - 1) % MOD; ll d = pow(a, b / 2) % MOD; return d * d % MOD; } ll comb(ll n, ll k){ if(!fact_init){ fact[0] = 1; fact[1] = 1; for(ll i = 2; i < max_n; i++){ fact[i] = fact[i-1] * i; fact[i] %= MOD; } fact_init = true; } ll ret = fact[n]; ret *= pow(fact[k],MOD-2); ret %= MOD; ret *= pow(fact[n-k],MOD-2); ret %= MOD; return ret; // X^(-1) = X^(p-2) (mod p) (Fermat's little theorem) } int main(){ cin.tie(0); ios::sync_with_stdio(false); int n; cin >> n; vector a(n); rep(i, n) cin >> a[i]; ll ans = 0; rep(i, n){ ans += comb(n-1, i) * a[i] % MOD; ans %= MOD; } cout << ans << endl; }