#!/usr/bin/env perl

use strict;
use warnings;

my $usage = "usage: $0 file.fq TopEntriesCount [append]\n\n";

my $fq_file = $ARGV[0] or die $usage;
my $top_entries_count = $ARGV[1] or die $usage;
my $append = $ARGV[2];

my $count = 0;
open (my $fh, $fq_file) or die "Error, cannot open file $fq_file";
while (my $line1 =  <$fh>) {
	my $line2 = <$fh>;
	my $line3 = <$fh>;
	my $line4 = <$fh>;
	
	chomp ($line1, $line2, $line3, $line4);
	
	$count++;
	
	if ($top_entries_count > 0 && $count > $top_entries_count) {
		last;
	}
	
	if ($append) {
		$line1 .= "/" . $append;
	}
	
	print join("\n", $line1, $line2, $line3, $line4) . "\n";
}

exit(0);