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: ['6463', '871', '5781', '283', '9653', 'f', '9661', '3365', '2889', '5499']

Answer: f


Question: ['w', '6291', '3939', '9569', 'u', '1635', '3359', '8335', 'n', '2799', '7359', 'k', 'm', '2817']

Answer: k, m, n, u, w


Question: ['7199', 'z', 'c', '7227', '1943', 'k', 'p', 'o', '6527', 'l', '1793', '5087', '4223', 'n', 'h', '2809', 's', 'u', 't', '887', '4035', 'q', '9889', 'l', 'f', 'e', 'q', 'f', '2725', '165', 't', '5155', '4959']

Answer:
c, e, f, h, k, l, n, o, p, q, s, t, u, z