#!/usr/bin/perl -w

#Written by, and many thanks to, Paul Schmidt <Paul.D.Schmidt@Dartmouth.EDU>

my ($last_ip, $ip, $name);
$last_ip='';
while(<>)
{
	chomp;
	next if /^\s*$/;
	($ip, $name) = split;
	if($ip eq $last_ip)
		{ print " $name" }
	else {
		print "\n$ip\t$name";
		$last_ip = $ip;
	}
}