use strict;
use warnings;

use Algorithm::Permute qw(permute);

my ($n,$i,@n,@temp,%arrangements);

$n = 8;        @n = (1..$n);
$i = 0;        $temp[&_fact($n)-1] = 1; # _fact := n!

$|++;
permute { $temp[$i++] = join(',',@n) } @n;
print STDERR scalar(localtime),$/;
@arrangements{@temp} = undef;
print STDERR scalar(localtime),$/;

sub _fact {
    my($n) = @_;
    my $t = 1;

    while ($n > 1) {
        $t *= $n;
        --$n;
    }

    $t
}