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: ['4637', 'f', '2639', '8623', 'w', 'e', 'k', '5503', 'x', '6633', '7553', '1455', 'u', '1773', 'r', 'u', '1489', 'u', '1303', '9683', 'z', '565', '7041', 'x', 'z', '9431', 'k', 'v', 'j', 'z', '5469', '5665', '4089', '4951', '8263', '5675', '4095', '7745', 'z', '2437', 'd', 'e', 'w']

Answer: d, e, f, j, k, r, u, v, w, x, z


Question: ['s', 'w', '8949', '4025']

Answer: s, w


Question: ['u', '8425', 'v', '4433', 'b', 'v', '8279', '3831', 'n', 'x', '9465', '6011', '9145', 'g', '8513', '3773', '9985', '2279', 'u', '4175', '4501', 'w', '5485', '9333', 'f', '4191']

Answer:
b, f, g, n, u, v, w, x