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', 'u']

SOLUTION: s, u

PROBLEM: ['n', 'h', 'j', '5945', '8511', 'y', '7739', '4717', '2483', 'p', '9545', '7647', '9863', '5591', '5393', 'i', '9225', '589', '1497', 'j', 'm', '2397', 'a', 'd']

SOLUTION: a, d, h, i, j, m, n, p, y

PROBLEM: ['i', 'y', 'q', 'r', '2815', 'n', 'h', 'r', 'q', '3231', 'w', '1319', 'n', 'z', 'g', 'b', '1191', '3105', '3119', 'z', '6317', 'w', '1073', 'f', 'b', '8921', '6655', 'l', '4207', '4799']

SOLUTION:
b, f, g, h, i, l, n, q, r, w, y, z