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.

['4927', 'h', 'x', '4719', 'j', 'f', '7797', 'l', 'i', 'q', 'x', 'i', 'k', '3215', 'k', '1625', 'g', 't', 'i', 'w', 'n', '6659', '8355', '831', 'h', '9723']
f, g, h, i, j, k, l, n, q, t, w, x

['4993', 'n', '7115', 'f', 'd', 'q', '249', '3203', 'w', '5689', '4103', '7129', '603', 'e', 'z', '5571', '3241', '6029', '2721', '8451', 'o', '7841', 'p', '6271', 'r', 'b', '9481', '4045', 'v']
b, d, e, f, n, o, p, q, r, v, w, z

['3055', 'v', 'm', 'a', '905', '6307', 'f', 'k', 'k', '1799', '561', 'w', 'n', 'g', 'y', '6169', '325', 'm', 'a', 'm', '9555', '6879', 'x', '2191', 'v', '7959', '1167', '7973', '7843', 'a', 'z', 'g', 'i', 't', '2457', '8019', 'w', 'q', '6363', 's', '7909']
a, f, g, i, k, m, n, q, s, t, v, w, x, y, z