use strict;
use warnings;
use Time::Piece;
my $format = "%d-%m-%Y";
while (my $date = <DATA>) {
    chomp $date;
    printf("%s %s legitimate\n", $date,
           (verify_date($date, $format) ? "is" : "is not"),
          );
}
sub verify_date {
    my ($date_in, $format) = @_;
    my $t = Time::Piece->strptime($date_in, $format);
    my $date_out = $t->strftime($format);
    return $date_in eq $date_out ? 1 : 0;
}

__DATA__
28-02-2004
29-02-2004
30-02-2004
28-02-2006
29-02-2006
30-02-2006