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: Welcome to Chuck Freedman who is coming to joing our great staff in my office, as a Special Assistant. We're very fortunate to have him joining the team.  Responser: congrats.chuck!!! Excellent addition..
