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: Thoughts and prayers to victims of the tragedy just now in Boston, as well as to volunteers and first responders.  Responser: And yes our prayers are with the victims of this horrific and senseless, needless tragedy in Boston!
