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.

['o', 'v', 'w', '7939', '571', '395', '3707', 'm', 'd', 'u', 'o', 'r', '4211', '9645', '8731', '2441', 'y', '8147', '8809', 'e', 'b', '6835', 'i', '2083', 't', '3481', 'f', 'f', '5559', '3601', 'e', '5637', '5185', 't', '6777', '3419', '8637', 'p', 's', 'o', 'x']
b, d, e, f, i, m, o, p, r, s, t, u, v, w, x, y

['8815', 'w', '8629', 'y', '3891']
w, y

['u', 'm', 'w', 'a', 'p', '2507', 'w', 'e', 'q', '2821', 'a', '7163', 'l', '3187', '9875', 'm', 'p', '3001', 'd', '1579', 'r', '675', '75', 'e', '6015', '4673', '1207', '7993', 'n', 'z', '7295', 'a', '6677', 'm', 'x', '4497', 'x', '9705', 'u']

a, d, e, l, m, n, p, q, r, u, w, x, z