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.

Ex Input:
['n', '7489', 'n', 'n', '9787', '7829', 'n', '3481', 'v', 'l', '8927', 'c', 'm', 'd']

Ex Output:
c, d, l, m, n, v


Ex Input:
['1971', 'g', 't', 't', 'x', 'q', 'o', 'm', 'h', '9481', '1729', '5527', 'u', '3157', 's', '8795', 'z', 'g', 'i', '1649', 'p', '65', 's', 'u', '6843', 'r', 'l', 'k', 'n', 's', 'm', '7991', 'u', 'a']

Ex Output:
a, g, h, i, k, l, m, n, o, p, q, r, s, t, u, x, z


Ex Input:
['k', 'v', 's', '8765', '3407', 't', '4571', '1433', '8489', '9035', 'a', '6039', '8581', 'f', 'w', '9725', '2281', '5027', '6989', 'd', 'g', 'c', 'f', 'h', '9217', '7289', '6719', 'k', 'b']

Ex Output:

a, b, c, d, f, g, h, k, s, t, v, w