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: @justinbieber Thank u Justin for this amazing concert. I can't believe that only u can provoke these thousand smiles these night#BelieveTour
This tweet contains emotions: 
joy, love, optimism