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:
['w', '1367', '5389', '9515']

Ex Output:
w


Ex Input:
['7301', '7999', 'x', 'r', '6881', 'e', '609', 's', '7495', 'a', 's', '1961', 'q', 'x', '373', '6289', '4847', '5969', 't', '5487', '7639', '9039', '2395', 'b', 'd', '1447', 's', '8137', 's', '443', 'f', 'z', '4823', 'k', 'i', 'o', '4739', 'w', 'f', '8853', 'a']

Ex Output:
a, b, d, e, f, i, k, o, q, r, s, t, w, x, z


Ex Input:
['w', '9291', '4829', 'q', '2501', 'v', 'f', '6261', '6803', '247', '2977', '8533', 'i', 'q', 'b', '7449', 'y', 's', '4471', '3193', '8277', '7735']

Ex Output:

b, f, i, q, s, v, w, y