#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long int n;
  cin >> n;
  long long int a[n], sum = 0;
  for (long long int i = 0; i < n; i++) {
    cin >> a[i];
    sum += a[i] * max(abs(n - i - 1), i);
  }
  cout << sum << endl;
  return 0;
}
