Assume we use Shift Cipher, and the message space is M = {aa, ab, bc}, where Pr[M = aa] = 0.3, Pr[M = ab] = 0.2, Pr[M = bc] = 0.5. In addition, we assume the key space is K = {0, 1, 2, ..., 25} and it is uniformly distributed, i.e., Pr[K = k] = 1/26, for any k [0, 25]. What is the probability of a ciphertext is XY?