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: ['s', '6723', 'l', '1573', '1129', 'n', '4277', '5003', 'y', '7563', 'c', '6747', '3105', 's', '3593', '8417', '8253', '4157', 'w', 'f', 'z', 'd', '9685', '1033', 'h', '4893', 't', 'j', '6821', 'z', 'a', 'u', '591', 'o', '1087', '2147', '1223', '2339', 'i', 'y', '9307', 'x', 'z', 'r', 'y']

Answer: a, c, d, f, h, i, j, l, n, o, r, s, t, u, w, x, y, z


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

Answer: m, r, v


Question: ['l', '419', '5993', 'b', '7595', 'g', 'j', '4437', 'q', 'k', 'q', 'w', '2835', '7121', 'u', 'i', 'c', '3827', 'r', 'v', '8025', '653', 'f', '2507', 'p', 'o', '6669', '2295', 'p', '787', '7089', 'g', 'z', '1163', '5881', 'z', '8335']

Answer:
b, c, f, g, i, j, k, l, o, p, q, r, u, v, w, z