#include <bits/stdc++.h>
#define int long long
using namespace std;

signed main() {
    ios::sync_with_stdio(0); cin.tie(0);
    int n;
    cin >> n;
    vector<int> a(n+1);
    for (int i = 1; i <= n; ++i) cin >> a[i];
    int res = 0;
    for (int i = 1; i <= n; ++i) {
        res += a[i] * i * (n - i + 1);
    }
    cout << res << '\n';
}