use strict;
use warnings;
use Algorithm::Permute;
my $p = new Algorithm::Permute([qw(c i o l n a o t)]);
my %seen_permutation;
my $length = 5;

while ( my @res = $p->next) {
    my @tmp = @res[0..$length - 1];            #get first n letters of @res;
    my $key = join('',sort {$a cmp $b} @tmp);  #return asciibetical list as key;

    unless ( $seen_permutation{$key} )     #skip if this pattern has been seen before
    {
        $seen_permutation{$key} = 1;
        my $r = new Algorithm::Permute([@tmp]);
        while ( my @sml = $r->next ) {
          print join ('',@sml), $/;
        }
    }
}