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: ['2995', '8179', '8131', '5655', 'j', 'q', 'l', '3193', '1823', 'y', 'n', '7645', 's', '5665', 'r']

SOLUTION: j, l, n, q, r, s, y

PROBLEM: ['2633', 'd', 'r', '8083', 'f', 'd', '5121', '8651', 'o', 'b', '811', '7551', 'x', 'p', 'm', 'v', 'm', '7833', '1959', 'y', 'p', '779', '1889']

SOLUTION: b, d, f, m, o, p, r, v, x, y

PROBLEM: ['5743', '9349', '4669', '9751', 'n', '7021', '3253', '2809', 'b', '1139']

SOLUTION:
b, n