How to track the number of Active instances of a Parallel Multi-instance Human Task

Hi

I have a Process which calls a Parallel Multi-Instantiated Human Task .
The Number of Iteration is determined from a Integer variable that has a whole number.

I store the value of the Variable as 3 or 4 and the same number of Instances are created.

Now I want to track the Iteration count. I need to assign a value of 1 to the First iteration, 2 to the second iteration and so on.
I can collect Case Id of each iteration. But Case Id is not helpful in my scenario.
I would like to assign something like 9-1 to the first Iteration , 9-2 to the second Iteration and 9-3 to the third Iteration.So for that I need to assign 1 to the first iteration, 2 to the second and so on.
Is there any way to achieve this ??
Is there any variable that tracks the iteration count. ??
There is something called numberOfInstances . Could We use this value to calculate our Iteration count.

I dont want to use sequential Iteration as it needs to happen in parallel.

All Ideas will be helpful.

Thanks