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: ['m', '7517', '9361', '9567', '8785', 'k', '5699', '3585', 'v', '1913', '1651', 'g', 'p', '2731', 'q', 'h', '467', 'r', '1091', '9801', 'a', '6645']

SOLUTION: a, g, h, k, m, p, q, r, v

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

SOLUTION: b, e, l, m

PROBLEM: ['l', '8385', '6827', '8629', 'o', 'u', 'y', 'm', '8443', '1585', 'n', '7853', '6115', '7111', '6809', 'y', 'f', '3181', '3405', '3845', 's', '9575', 'd', '6515', '4887', '181', '8703', '731', '1419']

SOLUTION:
d, f, l, m, n, o, s, u, y