Suppose you have a processor that can perform a single DES encryption or decryption operation in 2-26 seconds. Suppose you also have a large number of plaintext-ciphertext pairs for DES under a single, unknown key. How many hours would it take, on average, to find that DES key, using an exhaustive search approach and a single processor? How many hours would it take, on average, to find that DES key, using an exhaustive search approach and a collection of 2" processors?