Contact form 7 : Check wether one field is fild

I have a form build with Contact Form 7 where people could make a reservation for tickes and have the form send to a emailadrres. We have 2 kinds of tickets. So people could choose 1 quantity for ticket 1 and 0 for ticket 2.

Is it possible to code a validation that visitors should fill either a minimal ammount of 1 for either ticket 1 or ticket 2?

via Chebli Mohamed