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: ['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: ['c', '1693', 'l', 'u', 'x', '3609', 'h', '4159']

SOLUTION: c, h, l, u, x

PROBLEM: ['349', '4015', '3879', '5239', 'e', 'h', 'f', 'c', '2447', 'u', '23', 'v', '2073', 'e', 'u', '5291', 'r', '7189', '6847', '1797', '9855', '2799', 'b', '6025', '953', 'v', 'a', 'p', 'k', '1087', '6129']

SOLUTION:
a, b, c, e, f, h, k, p, r, u, v