How to keep only the last 30 events?

[achilleos]

Hello and thanks for the amazing tool.

I'd like to build a filter that deletes all events that are older than the last 30 events but I'm not sure how to do this.
Please note that I know how to build (and I'm not interested in) a filter that deletes all the events that are older than a given period of time.

Thanks!

[TheKorn]

You do it the same way, except instead of filtering on date you filter by event number.