for my $d qw(2005-12 2005-100 2005-1- 2005-12- 2005-123- 2005-1000) {
    printf "%-10s: ", $d;
    if ( $d =~ /(?>\d{4}-\d{1,3})(?!-)/ ) {
      print "yep\n" ;
    } else {
      print "nope\n";
    }
}