#!/usr/bin/perl -w

use strict;

sub common {
    my (%common, %test);
    $_ = shift;
    @common{@$_} = {} x @$_; # second use is scalar context
    while ( $_ = shift) {
        %test = ();
        @test{@$_} = () x @$_;
        delete @common{ grep { ! exists $test{$_} } keys %common};
    }
    return ( keys %common );
}

my @foo = (
    [1,2,3,5,8,9,4,5],
    [18,2,4,7,3,4.9],
    [2,3,6,5,9],
    [1,2,3,4,5,6,7,8,9,0],
    [1,2,3,5,8],
    [2,3,4,5,8,7],
    );

print "@{[common(@foo)]}$/";