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: ['j', '6675', 'u', 's', '705', '8227', 'f', 'w', 'n']

SOLUTION: f, j, n, s, u, w

PROBLEM: ['3561', 'd', '9697', 'd', '7761', 'a', '2833', 'c', '2921', 't', '691', 'g', '4797', 'b', '3913', 'f', 'q', '7807', 'j', '3577', 'j', '1775', '2897', '2589', '993', '8595']

SOLUTION: a, b, c, d, f, g, j, q, t

PROBLEM: ['x', 'b', 'j', '3855', 'i', 'u', 's', '2727', '3827', 'n', '3763', 'k', '8655', 'u', '1431']

SOLUTION:
b, i, j, k, n, s, u, x