Encryption: plain → right neighbor → cipher. Decryption: cipher → left neighbor → plain.
Up shift means cipher letter is directly above plain letter. fylm Wetlands 2013 mtrjm awn layn - fydyw lfth
If encryption = left shift of plain: plain f → left neighbor = d (cipher). So cipher d means plain f . We have cipher f , so plain = right neighbor of f = g. That’s not “film”. Encryption: plain → right neighbor → cipher