#!/usr/local/bin/perl
use strict;
use warnings;
use LWP::Simple;
use HTML::TreeBuilder;

	my $url="http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=1r9t&template=main.html";
	my $content=get ($url);	 
	my $chain;
	my @chains;
	my $p = HTML::TreeBuilder->new;
	$p->parse_content($content);
	my @tds = $p->look_down(_tag => q{td});
	for my $td (@tds)
	{

  	my $a = $td->look_down(_tag => q{a});
  	next unless $a;
  		if ($a)
			{
			my $href = $a->attr(q{href});
			if ($href =~ /&chain=(\w)"/)
				{
				print $1 qq{\n};
				$chain=$1;
				push @chains, $chain;    #I want to extract the chains....A,B,C,D,E,F,H,I,J,K,L
				}
			}
	$p->delete;
	
	}