/* VR370108 TRIPLETTEBIG */

#include <cassert>
#include <cstdio>
#include <fstream>
#include <iostream>
#include <algorithm>
#include <climits>

using namespace std;

int N;
const int IMPOSS = INT_MAX;
const int MAX_N = 10000;
int opt[MAX_N][MAX_N/3];
int vect[MAX_N];

int main(){
    FILE *in;
    in = fopen("input.txt", "r");
    assert(in);
    
    //int N;
    int fsf = fscanf(in, "%d", &N); fsf++;
    
    for(int i = 0; i < N; i++){
        int j;
        fsf = fscanf(in, "%d", &j);
        vect[i] = j;
    }

    fclose(in);

    sort(vect, vect+N);
    
    int i, k;
    int t = N/3;
    for(k = 0; k <= t; k++)
     for(i = 0; i <= N; i++)
        if(k == 0 ) opt[i][k] = 0;
        else if( 2*k > i) opt[i][k] = IMPOSS;
        else {
           opt[i][k] = opt[i-1][k];
           if( (i >= 2) && (opt[i-2][k-1] != IMPOSS) )
             opt[i][k] = min( opt[i][k],
                              opt[i-2][k-1] + (vect[i]-vect[i-1])*(vect[i]-vect[i-1]));
        }


    FILE* output;
    output = fopen("output.txt", "w");
    fprintf(output, "%d", opt[N][t]);
    fclose(output);

return 0;
}