#/usr/bin/perl
use strict;
use warnings;
use Regexp::Assemble;

my $str = '200908';

my $ra = Regexp::Assemble->new;
for my $y (5..8)
{
  for my $m (1..12)
  {
    my $datum=sprintf('20%02u%02u',$y,$m);
    $ra->add($datum);
  }
}

print $ra->re()."\n";

if ($ra->match($str)){
 print "ja\n";
}else{
 print "nein\n";
}