def build_generator(latent_size):
    # we will map a pair of (z, L), where z is a latent vector and L is a
    # label drawn from P_c, to image space (..., 28, 28, 1)
    cnn = Sequential()

    cnn.add(Dense(3 * 3 * 384, input_dim=latent_size, activation='relu'))
    cnn.add(Reshape((3, 3, 384)))

    # upsample to (7, 7, ...)
    cnn.add(Conv2DTranspose(192, 5, strides=1, padding='valid',
                            activation='relu',
                            kernel_initializer='glorot_normal'))
    cnn.add(BatchNormalization())

    # upsample to (14, 14, ...)
    cnn.add(Conv2DTranspose(96, 5, strides=2, padding='same',
                            activation='relu',
                            kernel_initializer='glorot_normal'))
    cnn.add(BatchNormalization())

    # upsample to (28, 28, ...)
    cnn.add(Conv2DTranspose(1, 5, strides=2, padding='same',
                            activation='tanh',
                            kernel_initializer='glorot_normal'))

    # this is the z space commonly referred to in GAN papers
    latent = Input(shape=(latent_size, ))

    # this will be our label
    image_class = Input(shape=(1,), dtype='int32')

    cls = Flatten()(Embedding(num_classes, latent_size,
                              embeddings_initializer='glorot_normal')(image_class))

    # hadamard product between z-space and a class conditional embedding
    h = layers.multiply([latent, cls])

    fake_image = cnn(h)

    return Model([latent, image_class], fake_image)