Given the emotion sadness and the tweet "@SkyUK not impressed by your customer support. Forcing customers to use fb chat or sms! Very slow. issue is not getting sorted", 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.