#include <algorithm>
#include <iostream>
#include <random>
#include <vector>

using namespace std;

int main() {
    int n;
    cin >> n;
    vector<long long> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a.begin(), a.end());
    long long sum = 0;
    int it = n - 2;
    for (int i = 0; i < n / 3; i++) {
        sum += a[it];
        it -= 2;
    }
    cout << sum << '\n';
}