TASK DEFINITION: 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.
PROBLEM: ['1801', 'q', '5101', '8863', '2309', 'p', '8789', '9529', '6135', '5523', 'f', '8889', '7639', 'k', '263', '5751', '5529', 'g', '1451', '4143', 'e', '6987']

SOLUTION: e, f, g, k, p, q

PROBLEM: ['6599', 'f', 'c', '661', 'q', 'e', '1951', 'f', 'f', 'a', 'd', '9521', '853', 'n', 'w', '6451', '5549', 'k', 't', 'l', 'z', 'm', 'k', '567']

SOLUTION: a, c, d, e, f, k, l, m, n, q, t, w, z

PROBLEM: ['3331', 'h', 'b', 's', 'o', '7499', 'i', 'q', 'q', 't', 'r', '4745', 'p', '1441', '7871', 'm', 'h', 'k', 'a', 'r', '6027', 'j', '7087', '515', '3485', 'm', '3993', 'a', '3611', '7393', 'e', 'g', '7561', 'v', '4269', 'r', 'y', '8639', 'f', 'd']

SOLUTION:
a, b, d, e, f, g, h, i, j, k, m, o, p, q, r, s, t, v, y