#include <bits/stdc++.h>
#define ll long long
#define endl "\n"
#define fi first
#define se second
#define pii pair<ll, ll>
#define mpii map<ll, ll>
#define vall(a) (a).begin(), (a).end()
#define all(a, n) a + 1, a + 1 + n
#define sze(a) (ll) a.size()
#define gcd __gcd
using namespace std;
const ll INF = 1e18;
const ll MOD = 1e9 + 7;
const ll MAXN = 1e5 + 10;

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