#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';

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

    int n;
    cin >> n;

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

        ans += (ll)(i + 1) * (n - i) * a[i];
    }
    cout << ans << newl;

    return 0;
}