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: ['1627', 'r', '2429', 'b', '4451', 's', 'k', 'm', '269', 'l', '709', 's', 'q', '985', 'x', 'j', 'k', 'k', '6603', 'v', '9497', '477', '5803', 'c', 't', 'f', '3189', '6419', '8561', '5709', 'u', 'z', '5717', '9711', 'w', 'y', 'm', 'v']

SOLUTION: b, c, f, j, k, l, m, q, r, s, t, u, v, w, x, y, z

PROBLEM: ['7591', '7521', 'm', '1429', 'x']

SOLUTION: m, x

PROBLEM: ['o', '2081', 'q', 'x', 'v', '5879', 't', '8319', 'y', '8543', 'p', 'f', 's', 'q', 'g', 'd', 's', 'b', '7033', 'j', '9837', '7105', 'y', 'c', '4915', '1379']

SOLUTION:
b, c, d, f, g, j, o, p, q, s, t, v, x, y