How to reset NavigationStack and Close the application.

Hello,
I want to close my application on OnBackButtonPressed() below is my code.
foreach (var page in Navigation.NavigationStack.ToList())
{
if (page.GetType() != typeof(BestRx.MainPage))
Navigation.RemovePage(page);
}
Application.Current.Quit();
return false;
Above code is working fine but only on double tap.Is there any other way to do on single tap?