In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
--------
Question: ['8815', 'w', '8629', 'y', '3891']

Answer: w, y


Question: ['p', '3981', 'e', '5949', 'p', '4075', '1919', 'w', 'r', '8059', '4303', 'f', '5201', '2255', '2737', '7395', '8809', 'j', 'z', 'n', '4797']

Answer: e, f, j, n, p, r, w, z


Question: ['r', '4525', 'a', '8163', 'r', 'm', 'q', '3527', 'p', '4705', 'g', '7053', 'c', '5561', 'o', '2667', 'z', 'b']

Answer:
a, b, c, g, m, o, p, q, r, z