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.
--------
Question: ['t', 'h', '6141', 'g', 'f', 'z', 'n', 'b', 'k', '9059', 'y', 'p', '4289', '2683', 'a', '3267', 'w', 'p', 't', '3623', '7759', 'a', 'o', 'm', '9815', 'q', 'u', '8051', '6871']

Answer: a, b, f, g, h, k, m, n, o, p, q, t, u, w, y, z


Question: ['4749', '4607', '625', '6907', 't', 'b', '8479', '6505', 'r']

Answer: b, r, t


Question: ['4839', 'm', 'v', 'f', '9905', '8669', 'y', '4723', '2663', '9369', 'w', 's', '3241', 's', 'g', '6639', '975', 'g', 't', 'h', 'c', '9743', '7115', '8265', 'n', 'u', 'h', '1599', 'i', 's', 'v', '477', 's', '4469', 'v', 'a', 'a', 'h', 'x', '7625']

Answer:
a, c, f, g, h, i, m, n, s, t, u, v, w, x, y