How to count entities that's match with a condition?

[Thành Vũ Trung]

Hi everybody, hope you are well now. I have a question.
How to count entities that's match with a condition in usergrid?
Ex:

   - Collection "posts" has 1000 entities, has some entities with {status:
   1}
   - I want to select count of entities that have {status: 1}

Hope any body can help me to explain this. Thank you so much.
-- 
Loyal.