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: Remembering those day when u still did'nt know kpop n thinking about how sad your life was without it - Kpop fan
This tweet contains emotions: 
sadness