GET the first result in HTTP request
Your question is not clear to me. First of all does your parser get the whole response? And second by first action do you mean "action_id":35"?
If both are true then your solution is simple. 

First you separate every comma ", " and put in a string array then you further split each index by ":" so the first part is the name "action_id" and the second is the value "35". I hope that helps . You can look up the split function, it's easy.

But if the above is not what you needed then I am afraid you cannot get only the first response, because that has to do with the server itself.

Here is a solution, do try it. 

I found an easier solution. Follow the example and replace the content and fields with your response content and you will be done in minutes.