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: ['1707', '381', '3957', '7853', '4987']

Answer: -1


Question: ['219', '2065', '4045', 'k', 'n', 's', 'z', '7239', '1043', 'r', '2333', 'q', 'k', 'b', '2013', 'g', '6925', '9835', 'a', '5377', 'k', '8005', 'p', '9753', 'm', '201', '2353', 'f', 'n', '89', 'q', 'p', '7847', 's', 'l', '3359', '2269', 'v', 'm', '8247', '9665', 'u', 'w']

Answer: a, b, f, g, k, l, m, n, p, q, r, s, u, v, w, z


Question: ['s', 't', '1899', '3039', 'n', '7153', '5601', 'c', '8997', 'g', '1643', 'x', 'f', 'w', 'f', 'j', '5913', '6277', '3189', '2385', '3849', 'w', 'h', '4679', 'l', '8039', '1693', '9503', 'p', '259', 'l', 'x', '907', 'w', 'i', '2407', '5019', '9639', 'b', 'a', 'm', '9059', '513']

Answer:
a, b, c, f, g, h, i, j, l, m, n, p, s, t, w, x