How would I edit this so if a password was entered wrong three times it'll exit the program?

Thanks for any help.

VB Code:
  1. Private Sub cmdLogin_Click()
  2.     Dim PassRS As Recordset
  3.     Set PassRS = Db.OpenRecordset("Login")
  4.     While Not PassRS.EOF And Not LoginOK
  5.         If (PassRS.Fields("password").Value = txtPassword.Text) And (PassRS.Fields("Username").Value = cboLogin.Text) Then
  6.             LoginOK = True
  7.             CurrentUser = PassRS("Username").Value
  8.         Else
  9.             PassRS.MoveNext
  10.         End If
  11.     Wend
  12.  
  13.     If LoginOK Then
  14.         Beep
  15.         frmIntro.Show
  16.         frmPassword.Hide
  17.         txtPassword = ""
  18.         LoginOK = False
  19.     Else
  20.         Response = MsgBox("Incorrect password", vbRetryCancel + vbCritical, "Access Denied")
  21.         If Response = vbRetry Then
  22.             txtPassword.SetFocus
  23.             txtPassword.SelStart = 0
  24.             txtPassword.SelLength = Len(txtPassword.Text)
  25.         End If
  26.     End If
  27. End Sub