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: ['d', 'r', '7769', '2159', 's', '3269', '5527', 'l', 'z', 'e', '5165', 'x', 'x', '8273', 'g', 'm', '7609', '4015', '6403', '3753', 'y', 'h', 'l', 'i', '389', 'm', 'u', '6845', 'r', 'c', '7571', '3355', '9755', 'n', '4625', 'p', '5645', '1703', '4439', 't', '8431']

SOLUTION: c, d, e, g, h, i, l, m, n, p, r, s, t, u, x, y, z

PROBLEM: ['w', 'n', '729', '2491', 'n', 'x', '915', '1869', 'z', '8491', '9947', '561', '829', 'n', 't', 'i']

SOLUTION: i, n, t, w, x, z

PROBLEM: ['6225', 'm', '1793', 'x', 'x', '1981', '4953', 'j', 'c', '105', 'h', '7973', '4873', '9857', '781', 'e', '6095', '3695', 't', 'x', '6725', 'v', '6467', '901', '6773', '2947', '95', 'z', '9487', 'h', 'k', '4601', 'x', '6407', '3583', '5687', 'j', '1765']

SOLUTION:
c, e, h, j, k, m, t, v, x, z