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: ['2527', '9123', '8717']

SOLUTION: -1

PROBLEM: ['h', '6865', '4019', '8571', 'y', '5575', '7835', '9537', 'n', '875', 't', 'a', 's', '2769', 'p', '1607', 'n', '4087', '961', '7869', '5085', '2131', '4867', 'j', 'h', 'y', '3105', '6609', 's', 'l', '3399', '5013']

SOLUTION: a, h, j, l, n, p, s, t, y

PROBLEM: ['5725', '4573', 'z', '1849', '1977', 'y', 'p', 'c', '5171']

SOLUTION:
c, p, y, z