input: 48x48 pixel gray values (between 0 and 255)
target: emotion category (beween 0 and 6: anger=0, disgust=1, fear=2, happy=3, sad=4, surprise=5, neutral=6)
auxiliary information (in separate file) which can be used during training, but not as input for predicting emotions at test time: identity (-1: unknown, positive integers = ID, not all contiguous integer values). The file has one entry per training example.