#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define clean(a,s) memset((a),0,sizeof((a)[0])*(s))
#define all(x) (x).begin() , (x).end()
#define fi first
#define se second
#define int int
using pii = pair<int,int>;
using ll = long long;
const int maxn = 2e5+5;
const int inf = 2e9;
const int mod = 1e9+7;
int n,a[maxn];
ll ans;
int32_t main () {
//freopen("in","r",stdin); freopen("out","w",stdout);
ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0);
cin >> n;
for(int i=1;i<=n;i++) cin >> a[i];
sort(a+1,a+n+1);
for(int i=1;i<=n;i++) ans += a[i];
for(int i=n;i>=3;i-=3) ans -= a[i-2];
cout << ans << endl;
}
