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: ['g', '7517', '3173', 'd', '2143', 'n', '8507', 'l', '8369', '225', 'e', 'l', '9511', 'p', '1317', '5651', 'p', '1125', 't', '739', '6453', 'l', 'g', '8555', '8075', 'x', 's', 'd']

SOLUTION: d, e, g, l, n, p, s, t, x

PROBLEM: ['y', 'u', 'c', '5909', 'x', '9865', 'e', 'h', '5125', '4719', 'w', '8855', 'i', 'd']

SOLUTION: c, d, e, h, i, u, w, x, y

PROBLEM: ['1193', 'z', '9723', '6671', 'e', 'f', '4597', '6955', '2081', 'm', '8551']

SOLUTION:
e, f, m, z