The input format is a JSON file with 1 JSONObject, "users", which contains a JSONArray of JSONObjects (each user), each of which contains 3 fields: an integer id to distinguish each user, a JSONArray entitled "items", which contains each entry in the document as a string, and (optionally) a JSONArray entitled "scores" which contains each corresponding score for the items (i.e. scores[0] contains the rating for items[0]).