#!/usr/bin/env perl

use strict;
use warnings;

my %master_letter_freq = qw{w 1 h 1 t 1 o 1 r 2 e 1};
my @result = qw{thew trow whew};

RESULT: foreach (@result)
        {
            my %seen;
            $seen{$_}++ for (split //,lc $_);

            foreach (keys %seen)
            {
                next RESULT if ($seen{$_} > $master_letter_freq{$_});
            }

            print "$_\n";
        }

foreach (@result)
{
    my %seen;
    $seen{$_}++ for (split //,lc $_);

    my $no_print = 0;
    foreach (keys %seen)
    {
        $no_print++ if ($seen{$_} > $master_letter_freq{$_});
    }

    print "$_\n" unless $no_print;
}