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: ['p', '9641', '8515', '1207', 'd', 'j', '6617', '5529', 'g', 'a', 'o', 'f', 'y', '4993', '4643', '6087', 'n', '3177', 'y', '9471', '1229', '8211', '7079']

SOLUTION: a, d, f, g, j, n, o, p, y

PROBLEM: ['5011', 'l', '925', 'e', 'b', '3077', 'm', '4541', '781']

SOLUTION: b, e, l, m

PROBLEM: ['u', '459', 'p', 't', 'v', 'u', 's', 'q', 'o', 't', 'm', 'l', 'q', 'p', '359']

SOLUTION:
l, m, o, p, q, s, t, u, v