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', 'n', '7583', '8697', '7927', 'l', '5003', '1363', 'p', 'e', 'q', '6227', '6915', '8619', '9011', 'n', '3063', '3799']

SOLUTION: e, l, n, p, q, r

PROBLEM: ['5499', 'm', '327', 'h', '5765', '4231', 'y', 'g', 's', '883', '9843', '2751', '8967', 'z', '2301', 'l', 'l', 'k', '7843', '7221', '3643', 'k', '5951', 'r', '9441', '235', '3835', 'l', 'e', 'y', '4061', 'l', '1177']

SOLUTION: e, g, h, k, l, m, r, s, y, z

PROBLEM: ['2325', 'g', '3653', 'y', '6251', 'o', '4653', 'h', '4521', 'c', '4757', 'm', '2015', '8801', 'z', '6445', 'z', '1735', '5655', 'k', '8567']

SOLUTION:
c, g, h, k, m, o, y, z