Instructions: 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.
Input: ['689', 'm', 'i', '1351', '2559', '9087', 'x', '4957', '5807', 'l', '9121', '2795', '1685', 'r', '7841', 'z', 'g', '3203', '7449', 'c', '8423', 'n', '487', 'l', '7239', 'q', '9093', '2785', 's', 'k', '3469', '9967', 'p', '4905', 'r', '5107', '2847', 'l', 'r', 'c', '1897', 'e', 'a', 'y']
Output:
a, c, e, g, i, k, l, m, n, p, q, r, s, x, y, z