private void btnATM(object sender, EventArgs e)
        {
            
           
            
            string securityCode = "RON";
            string customerPIN = txtPIN.Text.ToUpper();
            
            if (securityCode == customerPIN)
                {
                    MessageBox.Show("Welcome to Ron's ATM!", "Ron's ATM", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    lbAnswer.Items.Add("Welcome " + securityCode);
                }
            else
                {
                    Count++;
                    if (Count == 3)
                    {
                        MessageBox.Show("You are a crook. We are keeping your card!", "Ron's ATM", MessageBoxButtons.OK, MessageBoxIcon.Error);
                        this.Close();
                    }
                    else
                    {
                        MessageBox.Show("That is an incorrect PIN", "Ron's ATM", MessageBoxButtons.OK, MessageBoxIcon.Error);
                        txtPIN.Text = string.Empty;
                        txtPIN.Focus();
                    }
            }  
        
                     
             
        }