#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <cstdio>
using namespace std;
typedef long long int ll;

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll n; cin >> n;
    vector<ll> a(n);
    ll res=0;
    for(ll i=0;i<n;i++){
        cin >> a[i];
        res+=(i+1)*(n-i)*a[i];
    }
    cout << res << endl;
}