#include <bits/stdc++.h>
using namespace std;
#define fileio() freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define fastio() cin.tie(0), ios_base::sync_with_stdio(0)
#define pb push_back
#define sp " "
#define endl "\n"
#define pii pair<int, int>
#define st first
#define nd second
#define N 1000005
#define int long long
int arr[N];
int32_t main()
{
fastio();
int n;
cin>>n;
int sum = 0;
for (int i = 1; i <= n; i++)
cin>>arr[i], sum += arr[i];
sort(arr + 1, arr + 1 + n);
for (int i = n - 2; i >= 1; i-= 3)
sum -= arr[i];
cout<<sum<<endl;
cerr<<"time taken : "<<(float)clock() / CLOCKS_PER_SEC<<" seconds\n";
}
