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: ['k', 'j', 'v', '5277', '8607', 'n', '1109', 'e', 'k', '6579', 'o', '2909', 'u', 't', '9685', '8443', '9257', '8071', 'y', 'b', 'h', '4767', 'a', 'j', '8455', 'b', '7733', '2553', 'e']

SOLUTION: a, b, e, h, j, k, n, o, t, u, v, y

PROBLEM: ['r', 'y', 'c', '3211', '9245', '8459', '8521', '5781', 'w', 's', 'd', '5299', 'a', 'y', 'g', 'm', '6435', '8605', 'e', 'h', '6871', 's', '387', 'l', '5829', 'e', 'd', '9545', '2945', 'k', 'v', 't', '8449', '2199', 'm', '2599', '1489', '6623', 'x', 'l']

SOLUTION: a, c, d, e, g, h, k, l, m, r, s, t, v, w, x, y

PROBLEM: ['8975', '3427', '6001', '9323', 'k', 's', 'm', '103', '9535', 'x', '1279', '9917', 't', '6739', 'p', 'y', '2553', '6259']

SOLUTION:
k, m, p, s, t, x, y