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: ['4641', '2881', 'c', '4827']

Answer: c


Question: ['5039', '2227', 't', 'o', '3313', 'm', 'v', '637', '6773', 'v', 'c', 'l', 'y', 'u', '3823', '9669', 'k', 'h', '3589', 'b', 'i', '3833', 's', 'm', '8201', 'u', '3143', 'k', '4111', '9769', '425', '4339', '209', 'c', 'c', '669', '8201', 'u', '7443', '2387', '6919', 'b', 'b', '2873']

Answer: b, c, h, i, k, l, m, o, s, t, u, v, y


Question: ['k', '6397', 'q', '4119', '7225', 'w', 'e', '9869', '3583', '455', 'x', 'p', 'o', '9481', 'x', 'k', 'h', '9033', 'i', 'n', '8841', 'v', 'p', 'q', 'a', '2601', 'f', 'w', 'y', 'g', 's', '8629', 'j', '57', 'x', '335', 'u', '3473', '2407', 't']

Answer:
a, e, f, g, h, i, j, k, n, o, p, q, s, t, u, v, w, x, y