Найти максимальное число в матрице, которое повторяется не более одного раза

Var a:array[1..10,1..10]
 
Procedure TForm1.Button1Click
Var max,j,i,k,s:integer;
Begin 
StringGrid.Rowcount:=10;
StringGrid.ColCount:=10;
Randomize;
For i:=1 to 10 do 
For j:=1 to 10 do 
Begin 
A[i,j]:=Random(500)-42;
StringGrid1.Cells[j-1,i-1]:=IntToStr(a[i,j]);
End;
Begin
Max:=a[1,1];
K:=i;
S:=j;
For i:=1 to 10 do 
For j:=1 to 10 do 
If [i,j]>max then begin 
Max:=a[i,j];
K:=i;
S:=j;
End;
For i:=1 to 10 do 
For j:=1 to 10 do 
If a[i,j]=max then max:=max-1;
End;
For i:=1 to 9 do 
For j:=i+1 to 10 do 
If a[i] = a[j] then
Begin 
K:=i;
S:=j;
Label2.caption:=IntToStr(a[k,s])
End;
End;
End;
End.

unit Unit1;
 
interface
 
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.Grids;
 
type
  TForm1 = class(TForm)
    StringGrid1: TStringGrid;
    Button1: TButton;
    Label1: TLabel;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
   a:array[1..10,1..10] of  integer;
implementation
 
{$R *.dfm}
 
procedure TForm1.Button1Click(Sender: TObject);
 
 
Var max,j,i,k,m:integer;
Begin
StringGrid1.Rowcount:=11;
StringGrid1.ColCount:=11;
 
For i:=1 to 10 do
begin
For j:=1 to 10do
Begin
A[i,j]:=Random(500)-42;
StringGrid1.Cells[j,i]:=IntToStr(a[i,j]);
end;
end;
  Max:=a[1,1];
 
For k:=1 to 10 do
begin
For m:=1 to 10 do
Begin
If a[k,m]=max then  continue ;
If a[k,m]>max  then   Max:=a[k,m];
end;
end;
Label2.Caption:= ' max=  '+ IntTostr(Max) ;
 
 
End;
 
 
 
 
end.