procedure TForm1.FormCreate(Sender: TObject);
  var m,n,k:integer;
  begin
    randomize;
    m:=random(50);
    n:=random(50);
    k:=random(2);
    label1.Caption:=inttostr(m);
    label2.Caption:=inttostr(n);
    label3.Caption:=inttostr(k);
    if k=1 then
      label2.Caption:='+'
    else
      label2.Caption:='-';
end;

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
  var answer:integer;
  begin
    if key=chr(VK_RETURN) then
      begin
        if label2.Caption='+' then
          answer:=strtoint(label1.Caption)+strtoint(label3.Caption)
        else
          answer:=strtoint(label1.Caption)-strtoint(label3.Caption);
        if answer=strtoint(edit1.Text) then
          begin
            showmessage('回答正确');
            button1.SetFocus;
          end
        else
          begin
            showmessage('回答错误');
            edit1.SetFocus;
          end;
          edit1.SelectAll;
      end;
end;

function total(x,y:integer):integer;
begin
  total:=x+y;
end;

procedure TForm1.BitBtn1Click(Sender: TObject);
  Var x,y,z:integer;
  begin
    x:=3;
    y:=5;
    z:=total(x,y);
    label1.Caption:=inttostr(z);
  end;

program helloworld;

begin
    writeln('Hello, World!');
end.