Task: Categorize the tweet's emotional expression, classifying it as either 'neutral or no emotion' or as one or more of the specified emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that reflect the tweeter's state of mind.
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