#!/usr/bin/perl

use warnings;
use strict;
use Array::Diff;

my @old = ( 'a', 'b', 'c' );
my @new = ( 'b', 'c', 'd' );
    
my $diff = Array::Diff->diff( \@old, \@new );

my $cnt = $diff->count;
my @add = $diff->added;
my @del = $diff->deleted;
    
print "$cnt\n@add\n@del\n";