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: http://www.usatoday.com/story/sports/tennis/2015/01/30/mattek-sands-safarova-win-australian-open-doubles-title/22572957/  Responser: Way to go! You grand slammer you!!!
