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: ['2527', '9123', '8717']

Answer: -1


Question: ['f', 'w', 'y', 't', '5269', '9989', 'p', 'v', '6609', 'v', 'c', 'q', 'm', '6565', '189', 'm', '3617', 'b', '9147', '665', 'v', '5989', '1511', '3123', '6667', '4661', '185', 'b', '3405', 'b', '6027', 'n', '6973', '505', 'g', '815', '3439', '2069', '291', 'j', 'f', '1121', '8009', 'm', '8353']

Answer: b, c, f, g, j, m, n, p, q, t, v, w, y


Question: ['v', '5473', 'w', '3269', 'f', 'g', 'm', '7037', '961', 'y', 'o', '3851', '2321', 'u', 'b', '6619', 'y', 'o', '4523', 'l', 't', '5243', '9327', 'y', '1531', '7437', '5079', 'k', 'h', '6203', '3301', 'u', 'd', '1887', 'b', '6155', '3257', 't', '1539', '8387', '7911', 'q', 't', '9627']

Answer:
b, d, f, g, h, k, l, m, o, q, t, u, v, w, y