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: ['2819', 'k', 'u', 'a', '4575', 'a', 't', 'a', 'f', '1507', '415', 'w', 'o', 'o']

SOLUTION: a, f, k, o, t, u, w

PROBLEM: ['n', 'w', '6735', '3427', '6115', 'q', '7851', '3645', 'g', '6825', '6515', '4885', 'z']

SOLUTION: g, n, q, w, z

PROBLEM: ['h', 'k', '2019', 'i', '3867', 'm', 'l', 'p', 'u', 'p', 'z', 'k', '5173', 'r', 'g', 'o', 'g', 'l', 'g', 'm', 'y', '4115', 'v', '6031', '3143', '1891', 'h', '2901', 's', 'g', '4931']

SOLUTION:
g, h, i, k, l, m, o, p, r, s, u, v, y, z