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: ['1799', '6409', '9257', '5923', 'm', 'j', '2565', '715']

SOLUTION: j, m

PROBLEM: ['5431', 'o', 'u', 'l', 'f', 'd', 'r', '1479', '9357', 's', 'v', '6399', 'b', '7937', 't', '8497', 'r', '131', 'h', 'c', 'v', '8879', 'k', 'r', '4687', 'l', '1065', 'r', 'w', 'l', '3305', '461', 'q', 'h', 'b', 'e', 'e', 'w', '5999']

SOLUTION: b, c, d, e, f, h, k, l, o, q, r, s, t, u, v, w

PROBLEM: ['t', '9797', 'y', '8869', 'l', '2463', 'i', 'q', '9325', '6367', '221', 'o', 'z', '6517', '7301', '4441', 'x', 'j', 'z', '3437', 'e', 'q', 'f', 's', '5233', 's', 'b', 'p', 'y', 'f', '8211', 'z', 'n', 'z', 'x', 'x', 'q', 'e', '6027', '1245']

SOLUTION:
b, e, f, i, j, l, n, o, p, q, s, t, x, y, z