#include <bits/stdc++.h>
#define Task "task"
#define ll long long
#define F first
#define S second
using namespace std;
const int N = 2*1e5+5;
const ll INF = 1e18;

ll n,s;
ll a[N];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    if (fopen(Task ".inp", "r")) {
        freopen(Task ".inp", "r", stdin);
        freopen(Task ".out", "w", stdout);
    }

    cin >> n;
    for (ll i=1;i<=n;i++)
    {
        cin >> a[i];
        s+=a[i]*(i*(n-i+1));
    }
    cout << s;
    return 0;
}