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: RepubSenators meet w Obama. He said there would b a decision on Keystone pipeline b4 end of yr. waiting for StDept to forward https://twitter.com/ChuckGrassley/status/312387103843557376  Responser: Obama IS an idiot. Recognizing and announcing it merely demonstrate the superior intellect of Conservatives
