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.

Q: ['7997', 'm']

A: m
****
Q: ['s', '6723', 'l', '1573', '1129', 'n', '4277', '5003', 'y', '7563', 'c', '6747', '3105', 's', '3593', '8417', '8253', '4157', 'w', 'f', 'z', 'd', '9685', '1033', 'h', '4893', 't', 'j', '6821', 'z', 'a', 'u', '591', 'o', '1087', '2147', '1223', '2339', 'i', 'y', '9307', 'x', 'z', 'r', 'y']

A: a, c, d, f, h, i, j, l, n, o, r, s, t, u, w, x, y, z
****
Q: ['h', '4693', '4227', 'l', '4663', '4517', '3007', 'e', 'o', 'r', 'u', 'b', 'r', '6267', 's', 'i', '6247', 'a']

A:
a, b, e, h, i, l, o, r, s, u
****