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: ['3223', 'h', 'w', 'f', 'y', '1667', '8843', '8759', '9203', '3305', '3549', '5507', '6251', 't', '8319', '9121', '6643', 'u', '4273', '4429', '7543', '7909', '789', '9183', '5729', 'd', '7063', 'b', '6677', 'w', 'x', 'x', 'z', '769', 'p', 'd', 'h']

SOLUTION: b, d, f, h, p, t, u, w, x, y, z

PROBLEM: ['k', 'n']

SOLUTION: k, n

PROBLEM: ['1439', 'b', 'w', '5781', 'a']

SOLUTION:
a, b, w