#! perl -slw
use strict;

my $n = 2 ** @ARGV - 1;
my %hash;

for my $i ( 0 .. $#ARGV ) [
    open my $in, '<', $ARGV[ $i ] or die "$ARGV[ $i ] : $!";
    while( <$in> ) {
    	chomp;
        ( vec( $hash{ $_ }, 1, $i ) |= 1 ) == $n 
        	and print;
    }
}