Q: 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.
['m', 'z', 't', 'u', '4815', '2455', 'y', '3999', '5451', '6557', 'r', '6775', '6499', 'b', '6061', '5973', 'x', 'z', 't', '7573', 'l', 'w', '6985', 'q', 'd', 's', 'k', '4549', '2801', 'q', '9897', '3415', '2233', '7001', 'd', '547', 'g', '2661', 'l', 'f', 'e', '1147', 'p', '1441']
A:
b, d, e, f, g, k, l, m, p, q, r, s, t, u, w, x, y, z