C++ :

#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
int len[105],f[105][52];
bool solve(int n,int k);
//ifstream cin("chop.in");
//ofstream cout("chop.out");
int main()
{
    int n,k;
    cin>>n>>k;
    k+=3;
    for (int i=1;i<=n;i++) cin>>len[i];
    if (!solve(n,k)) cout<<-1<<endl;
    else cout<<f[n][k]<<endl;
    //system("pause");
    return 0;
}
bool solve(int n,int k)
{
    if (n<k*2) return false;
    memset(f,0x7f,sizeof(int)*105*52);
    sort(len+1,len+n+1);
    for (int i=0;i<=n;i++) f[i][0]=0;
    for (int j=1;j<=k;j++)
        for (int i=2*j;i<=n;i++)
        {
            f[i][j]=f[i-2][j-1]+(len[i]-len[i-1])*(len[i]-len[i-1]);
            if (i>2*j) f[i][j]=min(f[i][j],f[i-1][j]);
        }
    return true;
}

Pascal :

var
 a:array [1..100] of longint;
 f:array [0..100,0..50] of longint;
 n,m,xb,i,j,k:longint;
 function min(x,y:longint):longint;
 begin
  if x>y then
   exit(y) else
   exit(x);
 end;
begin
 readln(n,k);
 for i:=1 to n do
  read(a[i]);
 k:=k+3;
 if k*2>n then
 begin
  writeln(-1);
  halt;
 end;
 for i:=1 to n do
  for j:=1 to n-i do
   if a[j+1]<a[j] then
   begin
    m:=a[j];
    a[j]:=a[j+1];
    a[j+1]:=m;
   end;
 for i:=0 to 100 do
  for j:=0 to 50 do
   f[i,j]:=maxlongint;
 for i:=0 to n do
  f[i,0]:=0; 
 for i:=1 to n do
  for j:=1 to k do
   if j*2>i then
    break else
    f[i,j]:=min(f[i-1,j],f[i-2,j-1]+sqr(a[i]-a[i-1]));
 writeln(f[n,k]);
end.