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: Look who I met this evening at the US Open Tennis Championships - Rainn Wilson and Jason Biggs. They were so much fun!!  Responser: for just a moment, Jason Biggs was the spitting image of Peter Sellers, wow!
