# Codeblock 5a
def loss(target, prediction):    #(1)
    
    target = target.reshape(-1, S, S, C+5)                #(2)
    prediction = prediction.reshape(-1, S, S, C+B*5)      #(3)

    obj = target[..., 20].unsqueeze(3)      #(4)
    noobj = 1 - obj                         #(5)