Cart-rule conditions - adaptation

[pereca]

Hello,

 

I'm creating a cart rule condition in prestashop 1.5.6.1.  I want to connect the condition to the specific product. I came across the problem which I'm not able to solve:

 

I want this cart rule condition to be limited to 1 (one) item certain product in the cart, but there is no such option, as it sais:

The cart must contain at least  Product(s) matching the following rules

I wan't exactly one, not more then one. Any solutions or workarounds?

 

Thanks,