About how many times can you do ecstasy before it seriously damages your brain?

I am not looking for a lecture on how ecstasy is bad and I shouldn't do it. I just want to get some information.

I know doing it really frequently can fuck you up, but about how many times a year can you do it if your trying to be safe about it?

: http://alcoholdrugstreatment.info/about-how-many-times-can-you-do-ecstasy-before-it-seriously-damages-your-brain