#include <bits/stdc++.h>
using namespace std;
void chekarre(int* arr, int n) {
  cout << "[";
  for (int i = 0; i < n; i++) cout << arr[i] << " ";
  cout << "]" << endl;
}
bool comp(int i, int j) { return (i > j); }
int a[2000007];
int main() {
  int n;
  long long sum = 0;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  reverse(a, a + n);
  while (n) {
    for (int j = 0; j < n; j++) {
      sum += a[j];
    }
    n = n / 4;
  }
  cout << sum << endl;
  return 0;
}
