def lossAttack(model, images, labels, Loss):
    """ Computes the loss value for a batch of samples.
    model: instance of a nn.Module subclass
    images: pytorch tensor with dimensions [batch,channels,width,height]
    labels: pytorch tensor of shape [batch] containing the integer labels of the samples
    loss: callable, loss function
    outputs -> pytorch tensor of dimensions [batch] containing the negative loss values
    """
    loss = Loss(model(images).detach(), labels)
    return -loss