Valentine's Day
Valentine's Day|Cards
Valentine's Day|Flowers
Valentine's|Candy
Valentine's|Telegrams

##</code><code>##

Valentine's Day
Valentine's Day|Cards
Valentine's Day|Flowers
Valentine's
Valentine's|Candy
Valentine's|Telegrams

##</code><code>##

use strict;
#use warnings;
use Data::Dumper;



while(<DATA>) {
    chomp;
    my $path = $_;
    my @paths = split /\|/, $path;
    my $parent = $paths[-2];
    my $child = $paths[-1];
    my $prev_path;


    if ($prev_path !~/^$parent$/) {
        my $message = 'created new path!';
        my @new_paths = @paths;
        my $discard = pop @new_paths;
        my $new_path = join '|', @new_paths;
        print $new_path . "\t" . $message . "\n";
    }


    print $path . "\n";


    $prev_path = $path;
}

__DATA__
Valentine's Day
Valentine's Day|Cards
Valentine's Day|Flowers
Valentine's|Candy
Valentine's|Telegrams