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: ['i', 'x', 'n', 'w', '8915', 'd', 'd', 'd', '6025', '7861']

SOLUTION: d, i, n, w, x

PROBLEM: ['o', '4167', 'b', '1651', '8327', '9219', 'o', 'v', '5841', '6057', 'i', 'q', 'o', 'r', 'a', '7069', 'y', 'h', 'd', '3775', 'j', 't', '3663', '55', '7117', 'e', 'u', 'm', '931', '5777', '8773', '4891']

SOLUTION: a, b, d, e, h, i, j, m, o, q, r, t, u, v, y

PROBLEM: ['3733', 'r']

SOLUTION:
r