#!/usr/bin/perl -w

use strict;

my @strings = ('');

for my $a (1..10) {
    for my $b (0..(2**$a-1)) {
	push @strings, sprintf ("%0".$a."b", $b);
    }
}

print "->", join("<-\n->", grep /^(0|1(01*0)*1)*$/, @strings);