How to construe a dynamic "pic and choose" ?

Hello,

I would like to interpolate some points in a tree but I cannot find any solution. Without any strong experience with Grasshopper, I have tried different componants but to no avail.

Input is (as in the image below) is :

- m and n are input integers

- a tree with n branches, each with m points

- an list of n integers, (the ranks) each between 0 and (m-1)

Desired output is :

- a set of n points, each is at the rank defined in the list.

In the example below, output is the 0th point of the first branch, the 3rd point of the second branch, etc...

"Pick n'choose" seemed a good choice but it is suited if n and m are fixed (not our case). I tried "path mapping" but I was unable to use the list value as an index in the tree.

Any idea would be welcome (btw, I use RhinoWIP on mac). thks, thomas