vvAlice and Bob are using the ElGamal cipher with the parameters $=37$

and $=2$

$.$

Their parameters are small and we decide to crack the cipher.

Suppose Alice is observed sending public ephemeral key $=13$

and Bob sends public key $=35$

$.$

Alice is observed transmitting the ciphertext $=35$

$.$

a$)$ What is the masking key $$

$?$

b$)$ What is the plaintext?