#!/usr/bin/perl -w
use strict;
my @list_o_num = qw( 9 9 9 10 9 8 7 9 6 );
my %list_o_num = map {
  if ( exists $list_o_num{$_} ) {
    $list_o_num{$_}++;
  }
  else {
    $_ => 1;
  }
}
@list_o_num;
my @true_top_3 = sort { $b <=> $a } keys %list_o_num;