#include <bits/stdc++.h>
#define Task "bai1"
#define ll long long
#define ull unsigned long long
#define F first
#define S second
using namespace std;
const ll maxn = 2e5 + 5;
const ll MOD = 1e9 + 5;

ll n, x, ans;

int main()
{
    ios_base::sync_with_stdio(0);
    cout.tie(0);cin.tie(0);
    if (fopen(Task".inp","r"))
    {
        freopen(Task".inp","r",stdin);
        freopen(Task".out","w",stdout);
    }

    cin >> n;
    for (int i = 1; i <= n; ++i)
    {
        cin >> x;
        ans += x * i * (n - i + 1);
    }
    cout << ans;
}