About number of shared layers

[pangjh3]

UnsupervisedMT/NMT/src/model/attention.py

Line 76 in d5f2fc2

if self.n_enc_layers - k <= self.share_enc - 1:

In this line, If n_enc_layers is 4 and the share_enc is 3, I found that the shared layer is lstm_2 and lstm_3. That is, lstm_1 is not shared.
Is it a mistake? Or am I wrong?
Thank you very much!