unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Button1: TButton;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
num1,num2,num3,  max:integer;
begin
 num1 := strtoint(Edit1.Text);
 num2 := strtoint(Edit2.Text);
 num3 := strtoint(Edit3.Text);
if ( num1 > num2 ) then  max := num1
   else max := num2 ;

   if ( max < num3 )then max := num3;
   //  òàêèì  îáðàçîì  ñðàâíèëè âñå  òðè, òåïåðü íàèáîëüøåå â  max
   Form1.Label1.Caption:=inttostr(max);
end;

end.