#include <iostream>
#include <algorithm>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

deque<unsigned long long > d;
vector<unsigned long long > A, B, arr;
unsigned long long  n;

int main()
{
   ifstream  fin;
   ofstream fout;
   fin.open("maxsum.in");
   fout.open("maxsum.out");
   fin >> n;
   arr.resize(n);
   for(int i = 0; i < n; i ++)
   {
      fin >> arr[i];
   }
   sort(arr.begin(), arr.end());
   for(int i = 0; i < arr.size(); i ++)
   {
      if(i % 2 == 0)
         d.push_back(arr[i]);
      else
         d.push_front(arr[i]);
   }
   arr.resize(0);
   while(!d.empty())
   {
      arr.push_back(d.front());
      d.pop_front();
   }
   unsigned long long  ans = 0;
   for(int i = 0; i < n - 1; i ++)
      ans += arr[i] * arr[i + 1];
   ans += arr[0] * arr[n - 1];
   fout << ans << endl;
}