#!/usr/bin/perl -w
use strict;
use warnings;

my %duplicates;
while (<DATA>) {
    print if !defined $duplicates{$_};
    $duplicates{$_}++;
}

__DATA__
The quick red fox jumped over the lazy brown dog.
Time flies like an arrow, fruit flies like a banana.
Time flies like an arrow, fruit flies like a banana.
Now is the time for all good men to come to the aid of their party.
The quick red fox jumped over the lazy brown dog.
The quick red fox jumped over the lazy brown dog.
Time flies like an arrow, fruit flies like a banana.
Now is the time for all good men to come to the aid of their party.
Now is the time for all good men to come to the aid of their party.