@data = split;
($mask,$x,$y,$ftdens) = @data;

##</code><code>##

while(<>) {

##</code><code>##

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

my $file1 = "file1.txt";
my $file2 = "file2.txt";
my $outfile = "outfile.txt";

my @data1 = ();
my @data2 = ();
open(INFILE1,"$file1") or die "Couldn't open $file1: $!\n";
while(<INFILE1>) {
    chomp;
    my @line = split(/,/,$_);
    push(@data1,\@line);
}
close(INFILE1);

open(INFILE2,"$file2") or die "Couldn't open $file2: $!\n";
while(<INFILE2>) {
    chomp;
    my @line = split(/,/,$_);
    push(@data2,\@line);
}
close(INFILE2);

# now merge the data in the outfile
open(OUTFILE,">$outfile") or die "Couldn't open $outfile: $!\n";
my $count = 0;
foreach(@data1) {
    print OUTFILE @$_,$data2[$count]->[3];
    $count++;
}
close(OUTFILE);