#!/usr/bin/perl

use strict;
use warnings;

my @alphabet = ('a'..'z', 'A'..'Z', '_');

foreach my $ch1 (@alphabet) {
    print $ch1, "\n";
    foreach my $ch2 (@alphabet) {
        print $ch1, $ch2, "\n";
        foreach my $ch3 (@alphabet) {
            print $ch1, $ch2, $ch3, "\n";
            foreach my $ch4 (@alphabet) {
                print $ch1, $ch2, $ch3, $ch4, "\n";
                foreach my $ch5 (@alphabet) {
                    print $ch1, $ch2, $ch3, $ch4, $ch5, "\n";
                    foreach my $ch6 (@alphabet) {
                        print $ch1, $ch2, $ch3, $ch4, $ch5, $ch6, "\n";
                    }
                }
            }
        }
    }
}