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: Deeply troubled by today's Yellow Line Metro incident. We must ensure this can't happen again. Thoughts are with all affected riders.  Responser: Nothing will change. It WILL happen again. I'm done with Metro.
