#! perl
use strict;
use warnings;
use bigint;
use List::Util qw( max );
use Data::Dumper;

my @result = prime_factors(600_851_475_143);
#print Dumper \@result;
print max @result;

sub prime_factors
{
    my ($number) = @_;
    my  $divisor = 2;
    my  @factors;

    while ($number > 1)
    {
        if (($number % $divisor) == 0)
        {
            push @factors, $divisor;
            $number /= $divisor;
        }
        elsif ($divisor == 2)
        {
            ++$divisor;
        }
        else
        {
            $divisor += 2;
        }
    }

    return @factors;
}

##</code><code>##

12:58 >perl 609_SoPW.pl
6857
13:00 >