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: ['h', '1797', '8211', 'n', 'r', '7707', '2063', '4655', 'x', '5521', '8327', 'g', '7659', 'i', 'x', 'w', '9465', '4625', 'q', '5377', 'r', '225', 'r', 'i', 'e', '4163', 'g', 'g', '3537', 's']

SOLUTION: e, g, h, i, n, q, r, s, w, x

PROBLEM: ['f', '6729']

SOLUTION:
f