#!/usr/bin/perl

use strict;
use warnings;
use diagnostics;

use open IN => ':utf8';
binmode STDIN, ':utf8';
binmode STDOUT, ':utf8';

my %freq;
while (<>) {  # reads from STDIN or from all file names in @ARGV
    $_ = lc();
    s/[^a-z'-]+/ /g;
    for my $word ( split ) {
        $freq{$word}++;
    }
}
for ( sort { $freq{$b} <=> $freq{$a} || $a cmp $b } keys %freq ) {
    printf "%05d %s\n", $freq{$_}, $_;
    # or to list results on larger data sets without leading zeros:
    #  printf "%9d %s\n", $freq{$_}, $_;
}