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: ['s', 'w', 'c', '4137', 't', '2437', '349', 'h', '4539', 't', 'b', 'y', 'q', 't', '9087', 'c', '9489', '6285', '6247', '8353', 'n', 't', '8661', 'p', 'z', 'p', '773', 'w', 'q', '8081', 'r', 'u', 'z', 'k', 'a', 'b', '7513', '5549', '5325', '1101', 's', '6507', '3317']

SOLUTION: a, b, c, h, k, n, p, q, r, s, t, u, w, y, z

PROBLEM: ['1449', 'a', '6261', '303', '4651', 'n', 'u', '1595']

SOLUTION: a, n, u

PROBLEM: ['2343', 'b', '4287', 'g', 'k', '175', 'w', 'o', 'x', '6905', '4405', '97', '1619', '5957', '8745', 'k', '3545', '6467', '5063', '8589', 's', '6943', 'y', 'i', 'u', '6133', 'v', 'x', 'r', '2359', 'j', '103', '6707', '5217', '7799']

SOLUTION:
b, g, i, j, k, o, r, s, u, v, w, x, y