#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n + 1];
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  int minm = 10000000;
  for (int i = 1; i <= n; i++) {
    int sum = 0;
    for (int j = 1; j <= n; j++) {
      sum = sum + (a[j] * (i - 1 + abs(j - i) + j - 1));
    }
    minm = min(minm, sum);
  }
  cout << 2 * minm;
  return 0;
}
