private void Button_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("Nombre: " + nombre.Text + "\nNombre De Usuario: " + Username.Text
                            + "\nContraseña: " + password1.Password + "\nGenero : "
                            + genero.SelectedItem.ToString() + "\nFecha: " + gregoriano.SelectedDate.Value.ToShortDateString() + "\nCorreo electronico: "
                            + gmail.Text);
            Dueño n = new Dueño(nombre.Text, gregoriano.SelectedDate.Value.ToShortDateString(), 15, genero.SelectedItem.ToString(), gmail.Text, password1.Password, Username.Text);

            mnj.agregarCOn(n);

            IFormatter formatter = new BinaryFormatter();
            Stream     lstream   = new FileStream("contactos.txt", FileMode.OpenOrCreate, FileAccess.Write, FileShare.None);

            formatter.Serialize(lstream, mnj);
            lstream.Close();
            MessageBox.Show("registro Listo");
            this.Close();
        }