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: ['w', '491', 'x', 'u', 'z', 'q', '5411', '7629', '8261', '8629', '1441', '5139', 's', 'm', '6463', 'u', 'z']

Answer: m, q, s, u, w, x, z


Question: ['t', 't', 'p', '3245', 'x', 'g', 'i', 'u', '2599', '8613', 't', 'v', 'p', '5635', 'y', '9567', '5193', '8617', 'q', 'f']

Answer: f, g, i, p, q, t, u, v, x, y


Question: ['3841', '5137', '8311', 'x', '6047', 'c', '8743', 'c', '8959', '5479', 'n', 'a', 'x', '105', '8007', '6585', '9963', '5349', '4273', 'a', '1075', '6553', '7131', 'k', '9867', '1079', 'x', '6801', 'l', 'p', 'm', 't', '4389', '5885', 'l', 'b', 'x', '3807', '5933', '3691', 'u']

Answer:
a, b, c, k, l, m, n, p, t, u, x