#!/usr/bin/perl                                                                                
use strict;
use warnings;
use Set::Scalar;
use Data::Dumper;

my @arcb = ( 450, 625, 720, 645 );

my @arca = ( 625, 645 );

my $s1 = Set::Scalar->new(@arcb);

my $s2 = Set::Scalar->new(@arca);

@arcb = @{ $s1 - $s2 };

print Dumper( \@arcb );

__END__


$VAR1 = [
          450,
          720
        ];