#!/usr/bin/perl

use strict;
use warnings;

foreach my $char1 ('', 'a'..'z', 'A'..'Z', '_' ) {
    foreach my $char2 ('', 'a'..'z', 'A'..'Z', '_' ) {
        foreach my $char3 ('', 'a'..'z', 'A'..'Z', '_' ) {
            foreach my $char4 ('', 'a'..'z', 'A'..'Z', '_' ) {
                foreach my $char5 ('', 'a'..'z', 'A'..'Z', '_' ) {
                    foreach my $char6 ('', 'a'..'z', 'A'..'Z', '_' ) {
                        my $plain = $char1 . $char2 . $char3 . $char4 . $char5. $char6;
                        print $plain,"\n";
                    }
                }
            }
        }
    }
}