#include<bits/stdc++.h>

using namespace std;
using ll = long long;


int main()
{
    ll n;
    cin >> n;

    vector<ll> a(n);
    for(ll i = 0; i < n; i++)cin >> a[i];

    ll sum = 0;
    for(ll i = 0; i < n; i++) {
        ll cur = (i + 1) * (n - i);
        sum += a[i] * cur;
    }
    cout << sum << endl;
}

// 1 2 3 4