#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
typedef long long ll;
#define MOD 1000000007
using namespace std;
int main() {
    ll n;
    cin >> n;
    vector<ll> a(n + 1, 0);
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    ll ans = 0;
    for(int i = 1; i <= n; i++) {
        ans += a[i] * i * (n - i + 1);
    }
    cout << ans << endl;
}