<image>To ensure the secure transmission of information, there is a type of system called a Private Key Cryptosystem, with its encryption and decryption principles shown in the following diagram: __ Now, the encryption key is $$y={\log}_{a}(x+2)$$. As shown above, the plaintext “$$6$$” is encrypted to obtain the ciphertext “$$3$$”, which is then sent. The recipient uses the decryption key to decrypt and obtain the plaintext “$$6$$” again. Question: If the recipient receives the ciphertext “$$4$$”, what is the plaintext after decryption?