book.cpp

#include<iostream>
#include<cstdlib>
#include<algorithm>
#include<deque>

#define long long long
#define nln '\n'

using namespace std;

int main()
{
    cin.tie(0)->sync_with_stdio(0);
    cout.tie(0)->sync_with_stdio(0);
    //freopen("book.inp", "r", stdin);
    long n;
    cin >> n;
    deque<long> a(n);
    for (auto &i :a)
        cin >> i;
    sort(a.begin(), a.end());
    long ans = 0;
    if (n % 3 != 0)
        for (long i = 0; i < n%3; ++i)
            ans += a[0], a.pop_front();

    while (a.size())
    {
        ans += a[1]+a[2];
        for (long i = 0; i < 3; ++i)
            a.pop_front();
    }
    cout << ans << nln;
    return 0;
}