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: ['3019', 'g', 'q', 'u', '611', 'z', '3671', '8119', '1679', 'h', '2631', '655', 'k', '2837', 'e', 'f', 'e', 'f']

SOLUTION: e, f, g, h, k, q, u, z

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: ['s', 'b', 'm', 'p', '9753', '2489', 's', 'm', 'g', 'a', 't', 's', '7015', 'f', '1791', '3909', '9019', 'o', 'o', '2603', 's', '4727', '4531', '5943', 'y', '8589', 'j', '8377', 'o', 'c']

SOLUTION:
a, b, c, f, g, j, m, o, p, s, t, y