my $filename = shift @ARGV;
die "Usage: $0 FILENAME" unless defined $filename;
open my $fh, '<', $ARGV[0]
	or die "Could not open file '$filename': $!";

my %count;

INPUT: while (<$fh>)
{
	chomp;
	my ($ip1, $ip2, $bytes) = split /\s+/;
	($ip1, $ip2) = sort ($ip1, $ip2);
	$count{$ip1, $ip2} += $bytes;
}

OUTPUT: {
	local $, = "\t";
	local $\ = "\n";
	foreach (keys %count)
	{
		my ($ip1, $ip2) = split $;, $_;
		print $ip1, $ip2, $count{$_};
	}
}