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: ['f', 'j', '9195', '3155', '2855', '5333', '5263', '9279', '687', 'e', '3055', '7233', '13', 'j', 'p', 'i', '8327', 'm', 'h', '3977', 'h', '7997', 'a', 'h', '4661', 'x', '8237', 'a', '5009', 'o', 'p', 'z', '2293', 'q', 'p', '5469', 'k', 'q', 'b', 'n', '1967', '4991']

SOLUTION: a, b, e, f, h, i, j, k, m, n, o, p, q, x, z

PROBLEM: ['9637', '7813', 'r', '6489', '9557', '4575', 'r', '4549']

SOLUTION:
r