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: @Uber_RSA when you click over and over again for a cupcake but there are no vehicles available... #sadness
This tweet contains emotions: 
pessimism, sadness