#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < n; i++)
using ll = long long;
using graph = vector<vector<int>>;

const ll mod = 1000000007;
const int INF = 1001001001;

int main(){
    ll n; cin >> n;
    vector<ll> a(n);
    for(ll i = 0; i < n; i++) cin >> a[i];
    ll ans = 0;
    ll cnt = n;
    for(ll i = 0; i < n; i++){
        ans += a[i] * cnt;
        cnt = (n-1-i) * (i+2);
    }
    cout << ans << endl;
}