#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class T, class U> using Pa = pair<T, U>;
template <class T> using vec = vector<T>;
template <class T> using vvec = vector<vec<T>>;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll N;
    cin >> N;
    ll ans = 0;
    for(ll i=0;i<N;i++){
        ll a;
        cin >> a;
        ans += (i+1)*(N-i)*a;
    }
    cout << ans << "\n";
}