Task: Classify the mental state of the tweeter based on the tweet, determining if it is 'neutral or no emotion' or characterized by any of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust).
Tweet: It's my last week at CN! I'm gonna be sad to leave, but this will also be my first planned break since going into animation!
This tweet contains emotions: 
sadness