#include <bits/stdc++.h>

#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define endl "\n"
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rrep(i, n) for(int i = ((int)(n)-1); i >= 0; i--)
#define all(x) (x).begin(),(x).end()

using namespace std;
using ll = long long;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> P;
 
const int INF = 1e9;
//const ll INF = 1e18;
const double EPS = 1e-10;
const int MOD = 1e9+7;
const double PI = acos(-1.0);

ll Pow(ll x,ll n){
	ll res = 1;
	while(n > 0){
		if(n&1) res = res * x % MOD;
		x = x * x % MOD;
		n >>= 1;
	}
	return res;
}

ll nCr(ll n,ll r){
	ll res = 1;
	for(int i = n; i > n-r; i--) res = res * i % MOD;
	for(int i = 1; i <= r; i++){
		res = res * Pow(i,MOD-2) % MOD;
	}
	return res; 
}

int main()
{
	int n;
	cin >> n;
	vi a(n);
	rep(i,n) cin >> a[i];
	ll ans = 0;
	for(int i = 0; i < n; i++){
		ans = ans + a[i]*nCr(n-1,i);
	}
	cout << ans << endl;
	/*
	ll a,b;
	cin >> a >> b;
	cout << nCr(a,b) << endl;
	*/
	return 0;
}