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: ['1429', '7273']

Answer: -1


Question: ['s', 'w', 'c', '4137', 't', '2437', '349', 'h', '4539', 't', 'b', 'y', 'q', 't', '9087', 'c', '9489', '6285', '6247', '8353', 'n', 't', '8661', 'p', 'z', 'p', '773', 'w', 'q', '8081', 'r', 'u', 'z', 'k', 'a', 'b', '7513', '5549', '5325', '1101', 's', '6507', '3317']

Answer: a, b, c, h, k, n, p, q, r, s, t, u, w, y, z


Question: ['3167', '6947', '3783', '3723', '763', 'b', '2303', '2117', 's', 'q', 'z', '8573', '5647', '2255', '5953', 'u', 'j', 'u', '6097', '5393', '1807', '9471', 'h', '2381', '9429', '5521', 'y', 'p', 'x', '1439', 'b', 't', 'g', '1225', '9855', 'c', '7141', '1883', 'q', 'm']

Answer:
b, c, g, h, j, m, p, q, s, t, u, x, y, z