private void button1_Click(object sender, EventArgs e)
 {
     if (mng.RemoveStudentsSemester(Int32.Parse(id_input.Text)))
     {
         //FileStream file = File.Create("Uni");
         //BinaryFormatter bf = new BinaryFormatter();
         //bf.Serialize(file, Universal.instance);
         //file.Close();
         ManagerPanel managerpanel = new ManagerPanel(id);
         managerpanel.Show();
         this.Hide();
     }
 }