How to get points loceted right above certain points?

Hello dear community,

I have the following problem: I am given a could consisting of thousands of points located in a 3D-space. All points have the exactly same distance to one another.

Further on I am given a certain amount of points that are located at the bottom of the cloud.

How do I obtain all the points that are right above these certain points located at the bottom of the cloud?

Thank you for you help!