Problem 6. In class, we learned a simple symmetric shift cipher (a.k.a. Caesar cipher). The secret key K is an integer in {0,1,,25}. As always, we map each alphabet letter x{A,B,,Z} to an integer {0,1,,25}. The encryption and description are defined by Enc(x,k)=(x+k)mod26,Dec(x,k)=(xk)mod26. (a) As a warm-up, encrypt "CSCI IS COOL" using a Caesar cipher with k=F '. (b) Here's the ciphertext generated by the shift cipher. Find the corresponding plaintext (please explain the approach/strategy you used to find the key)