#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;

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

    cout << s << endl;

    return 0;
}