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: ['2181', '7019', 'l', 'z', 'z', 'y', '1245', '4179', '6951', '7249', '2723']

SOLUTION: l, y, z

PROBLEM: ['331', '125', 'u', 'a', 's', '6995', 'i', '3613', '9727', '7087', 'l', 'b', '8291', '813', 'i', '1169', '2159', 'd', '1451', 'q']

SOLUTION: a, b, d, i, l, q, s, u

PROBLEM: ['5999', '533', 'u', 'e', '2001', '6573', '3167', 't', 'p', 'g', 'r', '2205', '3031', '2635', '3883', 'n', 'c', 'j', 'j', '9737', '793', '9935', '4999']

SOLUTION:
c, e, g, j, n, p, r, t, u