How to setup a view in drupal 7 with taxonomy terms and show only the top level terms

Let's say that i have the Vocabulary named: Earth and i have the continents as top level terms and then the countries as second level terms etc. So my tree would be something like this: Europe -Greece -Italy -UK -France . . . etc Asia -China -Russia . . . etc How do i make a view that shows only the the top level taxonomy terms ? By creating a taxonomy term type view and adding a simple contextual filter in my view : Contextual filter: Taxonomy term: Parent term and choosing in the 'When the filter value is NOT available' the option : Provide default value / Fixed Value and in the Fixed Value input text field i enter 0. Now the view will try show up only the top level terms Europe,Asia,America etc but not the second level terms.