from math import log, exp

sequence = ["The", "cat", "sat", "<EOS>"]
print("Inputs:", sequence[:-1])
print("Targets:", sequence[1:])
p_correct = [0.8, 0.5, 0.25]
loss = -sum(log(p) for p in p_correct)/len(p_correct)
print("Loss:", round(loss, 3))
print("Perplexity:", round(exp(loss), 3))