use strict;
use warnings;

my @sites = qw|
   http://www.foo.com
   http://www.foo1.com
   http://www.foo2.com
   http://www.foo.com
   http://www.a.com
   http://www.a.com
   http://www.a.com
   http://www.a.com
|;

my %sites;
++$sites{$_} foreach @sites;

my @validsites   = sort { $a         <=> $b         } keys %sites;
my @popularsites = sort { $sites{$b} <=> $sites{$a} } keys %sites;

splice(@popularsites, 10); # Keep only the 10 most popular.

{
   local $, = "\n";
   local $\ = "\n";
   print 'Most Popular Sites',
         '------------------',
         @popularsites,
         '',
         'All Sites',
         '---------',
         @validsites;
}