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.
One example: ['8129', 'a', '4245', 'y', 'm', 'a']
Solution is here: a, m, y
Explanation: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.

Now, solve this: ['u', '949', 'q', '5109', '7103', '7503', 's', 'k', '1287', 'r', 'a', '5553', '509', 'x', 'b', '7253', 'b', 'n', '7751', '8199', '3411', '5607', 'q', 'u', 'c', 'o', '8537', 'f', '9943', 'e', 'q', '8897', 'm', 'm', 'a', '3763', 'a', 'u', 'h', 't', 'p', '5865', '4867', 'g', '2839']
Solution:
a, b, c, e, f, g, h, k, m, n, o, p, q, r, s, t, u, x