#!/usr/bin/perl

use strict; use warnings;
use File::Slurp qw(read_file);
use Array::Utils qw(intersect);

my $sfile = shift;
my $dbfile = shift;

my @series = map {/^(rs\d{1,18})$/} read_file $sfile;
my @dbpairs = map {/\s+(rs\d{1,18})\s+/} read_file $dbfile;

my @chosen = intersect @series, @dbpairs;

foreach my $p (@chosen){
	print "$p\n";
}