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: Do you believe that Congress should secure our border first before tackling immigration reform?  Responser: Secure borders b4 some terrorist group brings dirty bombs into the U.S.
