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: ['5553', 'f', '3881', '8867', 's', 'd', 'a', '375', '7889', '3949', '2905', 'w', 'q', 'q', 'd', '4203', 'i', '2601', 'y', 'p', 'k']

SOLUTION: a, d, f, i, k, p, q, s, w, y

PROBLEM: ['333', 'b', '261', 'k', 'p', '7861']

SOLUTION: b, k, p

PROBLEM: ['b', 'l', '1613', 'e', '1593']

SOLUTION:
b, e, l