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

#---------------

my $total_filtered = 0; 


my $input_file = "$input_dir"."input".".txt";
	
open(CGS, "<$input_file") or die "can't open $input_file\n";

my $cgs = <CGS>;

my $substring = substr($cgs, 2700000);
		
my @array = split(//,$substring);
		
foreach my $line (@array){
	if($line =~ /0/){
		$total_filtered++;
	}
}
print "$total_filtered\n";