How to count the number of comments and likes of a specific user in a group via the Callback API?

Question

In contact with

I want to gamify a Vkontakte group and I still can’t figure out how to use the Callback API to count the number of comments and likes of a particular user in a group. Who can did similar or will tell in what direction to dig. I did not find anything in the documentation, although it may be that I was looking badly or I don’t understand something.