use warnings; 
use Data::Dumper; 
open (FILE1, "$ARGV[0]"); 
open (FILE2, "$ARGV[1]"); 
 
my %data; 
my %data2; 
while (my $line1 = <FILE1>) 
{ 
    chomp $line1; 
    my @fields1 = split(/\t/, $line1); 
    $data{$fields1[0]} = [ $fields1[1] ]; 
} 
while (my $line2 = <FILE2>) 
{ 
    chomp $line2; 
 
    my @fields2 = split(/\t/, $line2); 
    unless (exists $data{$fields2[0]}) 
{ 
    $data2{$fields2[0]} = [ $fields2[1] ]; 
} 
    } 
foreach my $ID (keys %data2) 
{ 
    my ($info) = @{$data2{$ID}}; 
    print "$ID\t$info\n"; 
}