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: ['m', '8127', '7519', '4543', '2809', '9855', 'n', '6241', 'w', 'w', 'q', 'w', 'p', '8599', '7819', '3817', 'm', 'q']

A: m, n, p, q, w
****
Q: ['w', 'g', '1649', 'a', '2115', '6763', 'r', 't', 'l', 's', 'y', '5659', 'a', 'b']

A: a, b, g, l, r, s, t, w, y
****
Q: ['v', '4331', 'u', '4967', 'f', 'x', '3691', 'k', 's', 'x', '851']

A:
f, k, s, u, v, x
****