#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
  ll n; cin >> n;
  vector<ll> a(n);
  for(int i = 0; i < n; i++) cin >> a[i];
  ll sum = 0;
  for(ll i = 0; i < n; i++) sum += (i+1)*(n-i)*a[i];
  cout << sum << endl;
  return 0;
}