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: Blessed to see 24 years of life! Spent my birthday getting it in on the track! Operation: Moscow 2013 is in full throttle! Happy New Year!  Responser: Happy Birthday, and here's to some successful runs in August!
