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

die "Usage fileReference File2Check >outfile" if @ARGV != 2;

my ($fileRef, $file2Check) = @ARGV;

open my $fileREFIn, '<', $fileRef or die "unable to open $fileRef: $!";
open my $fileCHKIn, '<', $file2Check or die "unable to open $file2Check: $!";

my %seen = map { chomp; $_ => 1 } <$fileREFIn>;

print grep {! $seen{(split /,/, $_)[0]}} <$fileCHKIn>;