Given the emotion sadness and the tweet "When you burst out crying alone and u realize that no one truly knows how unhappy you really are because you don't want anyone to know", classify the intensity of the emotion displayed in the tweet. The classification options are: 0: no sadness can be inferred, 1: low amount of sadness can be inferred, 2: moderate amount of sadness can be inferred, 3: high amount of sadness can be inferred.
3: high amount of sadness can be inferred