private void submitButton_Click(object sender, EventArgs e)
        {
            string username = userNameTextBox.Text;
            string password = passwordTextBox.Text;
            string message="";
            if (username == "admin" && password == "admin")
            {

                Admin admin=new Admin();
                this.Hide();

                admin.Closed+=(s,args)=>this.Close();
                admin.Show();
            }
            else
            {
                int flag = 1;
                foreach (Stuff stuff in aStuffList)
                {
                    if ((stuff.Username == username) && (stuff.Password == password))
                    {
                        DateTime aDateTime = DateTime.Today.Date.Date;
                        aStuffManager.AttendanceSubmit(aDateTime, stuff.Id, out message);
                        MessageBox.Show(message);
                        userNameTextBox.Text = passwordTextBox.Text = "";
                        flag = 0;
                        break;
                    }

                }
                if (flag == 1)
                    MessageBox.Show("Invalid username or password");
            }
        }
        public void AdminRole()
        {
            string username = userNameTextBox.Text;
            string password = passwordTextBox.Text;
            string message = "";
            if (username == "admin" && password == "admin")
            {

                Admin admin = new Admin();
                this.Hide();

                admin.Closed += (s, args) => this.Close();
                admin.Show();
            }
            else
            {
                MessageBox.Show("Admin username and password is incorrect", "Error",MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }