procedure TForm1.Button1Click(Sender: TObject);
begin
if (txtUsername.Text = 'usuario1') and (txtPassword.text = '1234') or
(txtUsername.Text = 'usuario2') and (txtPassword.text = '5678') or
(txtUsername.Text = 'usuario3') and (txtPassword.text = '9123') or
(txtUsername.Text = 'usuario4') and (txtPassword.text = '4567')
then
begin
end
else
MessageDlg('Acceso Denegado: Username y/o Password Incorrectos', mtinformation, [mbok], 0);
end;