var a:array[0..10000]of integer;
    max,i,j,n,k,l,group1,group2:longint;
begin
 read(n);
 for i:=1 to n do
  read(a[i]);
 for i:=1 to n-1 do
  begin
   k:=i;
   max:=a[i];
   for j:=i+1 to n do
    if a[j]>max then
     begin
      max:=a[j];
      k:=j;
     end;
    a[k]:=a[i];
    a[i]:=max;
  end;
  for i:=3 to n do
  if group1<group2 then
   group1:=group1+a[i]
  else
   group2:=group2+a[i];
 writeln(abs(group1-group2));
end.

this is wrong approach.

the right solution is DP or bruteforcing all combinations.

Someone have function DP of this problem

use BruteForce my program with it works good
difficulty of my algorithm is O(n* pow(2,20) = O(n*1048576)