program stone;
const nmax=20;
var
 i,k,n:byte;
 x:longint;
 a:array[1..nmax] of longint;
begin
read(n);
For i:=1 to n do read(a[i]);
 For i:=2 to n do
  For k:=n downto i do
   If a[k-1]>a[k] then
   begin
    x:=a[k];
    a[k]:=a[k-1];
    a[k-1]:=x;
   end;
 while n>1 do
 begin
   a[n-1]:=a[n]-a[n-1];
   dec(n);
  For i:=2 to n do
   For k:=n downto i do
    If a[k-1]>a[k] then
    begin
     x:=a[k];
     a[k]:=a[k-1];
     a[k-1]:=x;
    end;
 end;
write(a[1]);
read;
end.

May be I am too self-confident, but I am sure my program must work. But the fifth test refutes my confidence. If you are able to help, please,try to find mistake and write where it is=)

Your algo is incorrect.

Test:
5
3 3 3 4 5

Answer: 0

Thank you, I understood, I will at a new algo.