Definition: Given a 'poster' sentence and a corresponding 'response' (often, from Facebook or Reddit)classify the sentiment of the given response into four categories: 1) Positive, 2) Negative, 3) Neutral, and 4) Mixed if it contains both positive and negative.
Input: Poster: Join me on UNation ... It'll be THE spot to see my races live & be up to date w/me. Thanks in advance. http://bit.ly/UNATIONfriendsandfamily  Responser: What's the closet track meet to Mississippi, you all will be competing in?
