What does this mean: Contest open to entrants ages 13-18 only.?

Do i have to be between 13-18 years or is it ok to be above 18 (18+)?

I'm from the Netherlands and it's quite confusing. Thanks for the answers.

Kiteman4 years ago
You must be *below* 18 to enter.

Aged 13, 14, 15, 16, 17, 17yrs and 11 months, OK.

Aged 18, not OK
what about 17 years 11 months 30 days 23 hours 59 minutes and 59 seconds.
:-p
Doesn’t cut butter in February and a few others:-D