#include <bits/stdc++.h>
using namespace std;
int sum(long long a) {
  int sum = 0;
  while (a > 0) {
    sum = sum + (a % 10);
    a = a / 10;
  }
  return sum;
}
int count_digit(long long n) {
  int count = 0;
  while (n > 0) {
    n = n / 10;
    count++;
  }
  return count;
}
int binarySearch(int x, int y, long long z, long long v[]) {
  int low = x;
  int high = y;
  int mid = x + (y - x) / 2;
  while (low <= high) {
    if (v[mid] == z) return mid;
    if (v[mid] < z) return binarySearch(mid + 1, high, z, v);
    if (v[mid] > z) return binarySearch(low, mid - 1, z, v);
  }
  return -1;
}
long long modularExponentiation(long long x, long long n, long long M) {
  if (n == 0)
    return 1;
  else if (n % 2 == 0)
    return modularExponentiation((x * x) % M, n / 2, M);
  else
    return (x * modularExponentiation((x * x) % M, (n - 1) / 2, M)) % M;
}
long long binaryExponentiation(long long x, long long n) {
  if (n == 0)
    return 1;
  else if (n % 2 == 0)
    return binaryExponentiation(x * x, n / 2);
  else
    return x * binaryExponentiation(x * x, (n - 1) / 2);
}
set<long long> s;
void genrate(long long n, int len, int max) {
  if (len > max) return;
  s.insert(n);
  genrate(n * 10 + 1, len + 1, max);
  genrate(n * 10 + 0, len + 1, max);
}
void max_heap(int a[], int n, int index) {
  int left = 2 * index;
  int right = 2 * index + 1;
  int largest;
  if (left <= n && a[left] > a[index])
    largest = left;
  else
    largest = index;
  if (right <= n && a[right] > a[largest]) largest = right;
  if (largest != index) {
    swap(a[index], a[largest]);
    max_heap(a, n, largest);
  }
}
void heapify(int a[], int n) {
  for (int i = n / 2; i > 0; i--) max_heap(a, n, i);
}
int a[10000];
int arr[10000];
void segmentTree(int node, int start, int end) {
  if (start == end) {
    arr[node] = a[start];
    return;
  }
  int mid = (start + end) / 2;
  segmentTree(2 * node, start, mid);
  segmentTree(2 * node + 1, mid + 1, end);
  arr[node] = arr[2 * node] + arr[2 * node + 1];
}
int query(int l, int r, int start, int end, int node) {
  if (r < start || l > end) return 0;
  if (l <= start && end <= r) return arr[node];
  int mid = (start + end) / 2;
  int p1 = query(l, r, start, mid, 2 * node);
  int p2 = query(l, r, mid + 1, end, 2 * node + 1);
  return p1 + p2;
}
int b[1001][1001];
void printup(int l, int r, int row) {
  if (l == r) {
    cout << b[row][l] << " ";
    return;
  }
  printup(l + 1, r - 1, row - 1);
  cout << b[row][l] << " " << b[row][r] << " ";
}
void printdown(int l, int r, int row) {
  if (l == r) {
    cout << b[row][l] << " ";
    return;
  }
  cout << b[row][l] << " " << b[row][r] << " ";
  printdown(l + 1, r - 1, row + 1);
}
int check(int x) {
  map<int, int> m;
  int temp = x;
  if (temp == 0) m[x]++;
  while (temp) {
    m[temp % 10]++;
    temp = temp / 10;
  }
  temp = 99999 - x;
  if (temp == 0) m[temp]++;
  while (temp) {
    m[temp % 10]++;
    temp = temp / 10;
  }
  if (m.size() == 2)
    return 1;
  else
    return 0;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int tests = 1;
  while (tests--) {
    int n;
    cin >> n;
    vector<long long> a(n + 1);
    for (int i = 1; i <= n; i++) {
      cin >> a[i];
    }
    a[0] = -1;
    long long res = 0;
    long long cnt = 0;
    long long sum = 0;
    sort((a).begin(), (a).end());
    reverse(a.begin() + 1, a.begin() + n + 1);
    for (int i = 1; i <= n; i++) {
      sum = sum + a[i];
      if (i == pow(4, cnt)) {
        res = res + sum;
        cnt++;
      }
    }
    cout << res;
  }
}
