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: Congrats to Serena Williams on her 22nd grand slam title! One of the greatest athletes of all time . ps this tweet made me laugh  Responser: I love Serena, gonna have to watch on I Player! Im a aspiring tennis player as well, looking up to her!!
