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: ['9117', '1153', 'f', 'b', '9979']

Answer: b, f


Question: ['z', '5601', '5675', 'w', 's', 'z', '9213', '9563', '1699', 'p', 'g', 'm', 'c', '9279', '4481', 'p', 'n', '2389', 'c', '503', '1901', '8827', '1701', '1607', '5633', 'a', 'z', 'g', '3175', 's', 'l', 'l', '6811', '1821', '693', '8277', 'q', '8623', 'o']

Answer: a, c, g, l, m, n, o, p, q, s, w, z


Question: ['5739', '2791', 'g', '1333', 'c', 'u', '9509', 'l', 'e', '1405', '2333', 'g', 'x', 'p', 'c', 'g', 't', '1687', 'q', 'v', '7543', '9847', 'k', 'b', '4361', '5473', '2687', '8567', 'x', '4523', '6533', '97']

Answer:
b, c, e, g, k, l, p, q, t, u, v, x