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: ['5973', 'h', '4081', 'i', '8059', 'w', 'j', '6175', 'w', '8685', '5811', 'k', 'n', '5577', '9817', 'v', '8617', 'u', 'y', '3921', 'b', '1027', '5405', 'a', '3501', '6659', 's', 'e', '157']

Answer: a, b, e, h, i, j, k, n, s, u, v, w, y


Question: ['9579', 'm', 'v', 'r']

Answer: m, r, v


Question: ['s', 'p', '9109', 'c', 'j', 'h', 'a', '6229', '4421', 'l', 'r', 'r', 'u', '9405', '4405', 'd', '5347', '5855', 'o', 'u', 'v', 'k', 'u', 's', '6421', 'm', '9497', 'x', 'g']

Answer:
a, c, d, g, h, j, k, l, m, o, p, r, s, u, v, x