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: ['f', 'p', 'n', '839', '9229', 'r', '7661', 'c', '4383', 'u', 'k', '5321', '3181', '1785', 'w', 'k', '8721', '7855', '4093', '6495', 'q', '2467', 'g']

SOLUTION: c, f, g, k, n, p, q, r, u, w

PROBLEM: ['7155', 'y', '145', '7147', 'u', '8453', 'd', '3693', '6471', '5289', 'n', 'p', '8289', '2929', '199', 'e', '8377', '8937', '5315', 't', 'l', '7715', 'c', 'y', 'f', '9999', 'p', '3655', '5489', 'q', '2321', '9881', '2265', 'n', 'v', '455']

SOLUTION: c, d, e, f, l, n, p, q, t, u, v, y

PROBLEM: ['2505', '2119', 'x', 'g', 'j', 'n', '8025', 'u', '5391', 'z', '1761', 'c', '3527', 'q', '2673', '8911', '9689', '6519', '3033', '865', 'n', '49']

SOLUTION:
c, g, j, n, q, u, x, z