Freeform Drag and Drop with Multiple Correct Answers in One Area

I'm creating a freeform drag and drop interaction where students need to "build an atom. The atom has 5 protons and 6 neutrons that all need to go into the drop target in the middle, but I'm giving them 11 of each for critical thinking purposes. My problem is I can't guarantee that they will pick 5 protons (ovals 1-5) and 6 neutrons (ovals 6-12) from the entire group (ovals 1-22) and those are the ones marked as correct in the form view. So, is it possible to use a variable that somehow indicates "when there are 5 ovals between numbers 1-11 and 6 ovals between numbers 12 and 23, the interaction is correct"? I'm not even sure I'm explaining this well. I've attached a pic of the slide; the white rectangle in the middle is the designated drop target. Thanks for any suggestions anyone might have!