use strict;
use warnings;

use Quantum::Superpositions;

my ($str1, $str2) = @ARGV;
die "Usage: $0 <string1> <string2>" if ! defined $str2;

print In_Common($str1, $str2), "\n";

sub In_Common {
    my ($str1, $str2) = @_;
    return join '', 
        eigenstates(
            all(
               any( split( //, $str1 ) ),
               any( split( //, $str2 ) )
            )
        );
}

##</code><code>##

use strict;
use warnings;

use Quantum::Superpositions;

print In_Common( @ARGV ), "\n";

sub In_Common {
    return join '', 
        eigenstates(
            all(
                map { any( split( //, $_ ) ) } @_
            )
        );
}