#include<bits/stdc++.h> using namespace std; #define ll long long #define co cout<< // stuff void solve(){ ll ans=0; ll n; cin>>n; ll arr[n+5]={}; for(int i=1;i<=n;i++) cin>>arr[i]; sort(arr,arr+n+1); for(int i=n;i>=1;i-=3) ans+=arr[i]+arr[i-1]; co ans; } int main(){ ios_base::sync_with_stdio(0);cin.tie(0); int _=1; // cin>>_; while(_--) solve(); }