$($RSA public key cryptosystem$)$

Bob chooses the secret primes $p=11$ and $q=23.$ Bob chooses the encryption exponent $e=7.$ Bob publishes $N=253$ and $e=7.$

Bob receives the ciphertext $c_2=163$ from Alice. Compute the plaintext $m_2$ that Bob obtains by deciphering $c_2.$