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: @BorisJohnson unhappy about the cost of leaving the EU ? If only you had published your letter outlining the reasons to stay instead. Idiot.
This tweet contains emotions: 
anger, sadness