For example, Kalchbrenner et al. [12] used a combination of a convolutional neural network and a recurrent neural network, Sutskever et al.<cite> [22]</cite> used a large and deep Long Short-Term Memory (LSTM) model, Cho et al. [5] used an architecture similar to the LSTM, and Bahdanau et al. [2] used a more elaborate neural network architecture that uses an attentional mechanism over the input sequence, similarly to Graves [9] and Graves et al. [10] .