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: ['s', 'j', '6779', '1535', 'd', 'e', 'u', '3023', '241', '9115', 'h', '8003', '3755', 'q', 'm', '2725', 'x', 'y', 'n', 'm', 'j']

SOLUTION: d, e, h, j, m, n, q, s, u, x, y

PROBLEM: ['n', 'g', 'u', '2873', 'k', '4411', 'w', '8179', 'w', 'w', 'f', 'g', 'e', '7837', '3055', 'z', 's', '6037', 'n', '1479', 'c', '5311', 'i', 'w', 'z', '1891', '9663', 'y', 'f', 'h']

SOLUTION: c, e, f, g, h, i, k, n, s, u, w, y, z

PROBLEM: ['o', 'n', 'd', 'h', 'r', '4373', 'u', '219', '4449', '9657', '1435', '3581', 'y', '467', '6923', 'l', 'g', '1521', '7739', '163', '4175', '619', '5327', 'n', '6737', 'y', '5545', '8381', '8387', 'l', 'd', '5519', 'a', 'q', '8155']

SOLUTION:
a, d, g, h, l, n, o, q, r, u, y