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: ['r', 's', '2471', 'n', '635', 'k', '3551', '7041', '8765', '1221', '8439', '7773', '6471', 'u', 'p', '2093', '6479', '1435', '6881', 'a', 'y', 'm', 'r', '1627', 'w', 'k', 'b', '3095', '9059', '285', 'y', 'a', 'm', 'x', '637', 'i', '3407', 'e', 'e']

SOLUTION: a, b, e, i, k, m, n, p, r, s, u, w, x, y

PROBLEM: ['q', 'g', 's', 'g', 'z', '987', '777']

SOLUTION: g, q, s, z

PROBLEM: ['p', 'l', 'p', '893', '8175', 'i', 'v', '5069', '2021', '4867', '5039', 'x', 'f', '8705', 'w', 'v', '4407', '8061', '8393', '2347', '1011', '1003', '1033', '1205', 'y', '2531', 'v', '8333', 'c', '8195', 'm', 'b', '8129', 'u', 't', 'u', 'v', '6159', '8751', '4683', '1655', 'h']

SOLUTION:
b, c, f, h, i, l, m, p, t, u, v, w, x, y