in my dictionary file, there are multiple left-hand-only words sharing the longest length. the following code outputs all of them.

@ARGV = qw(/usr/dict/words);

my $len = 0;
my @largest;

while (<>)
{
    chomp;

    next unless length >= $len && /^[qazwsxedcrfvtgb]+$/i;

    if (length > $len)
    {
        @largest = ();
        $len = length;
    }

    push @largest, $_;
}

print join(', ', @largest), $/;
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this gives the full set of answers: 'aftereffect', 'desegregate', 'exacerbated', 'exacerbates', 'exaggerated', 'exaggerates', 'reverberate', and 'vertebrates'.