use strict;
use warnings;

my %data;

open (DATA1, "<", "data1.txt") or die "cannot open file";

while (<DATA1>) {
	my @line = split (/\t/, $_);
	$data{$line[0]} = $line[1];
}

my @k = keys %data;
foreach my $key (@k) {
	print "$key, $data{$key}\n";
}
close DATA1;

open (DATA2, "<", "data2.txt") or die "cannot open file";
print "found:\n";

while (<DATA2>) {
chomp;
if (exists $data{"$_"}) {print "$data{$_}\n";}

close DATA2;