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', '2507', '3091', 'g', '7643', '2573', 'w', 'r', '1977', 'q', 'c', 'j', '1335', '9671', '7317', '567', '2041', '5777', 'w', 'm']

SOLUTION: c, g, j, m, q, r, s, w

PROBLEM: ['p', 'v', '1099', 'y', '1313', 's', '181', 'u', 'e', 'u', '8435', '4125', '8661', 'c', '4605', 'f', 'x']

SOLUTION: c, e, f, p, s, u, v, x, y

PROBLEM: ['3579', '5849', 'p', 'c', '8077', 'x', '6691', '3215', '7787', '5031', '7855', 'c', '8845', '7071', '6179', 'w', 'y', 'm', '6201', '1893', '6363', '4841', '7873', '4463', 'o', '6519', 'p', '8157', '8081', 'n', '3033', 'v', '2393', '4897', 'o', '1111', '2729', 'p', '7765', '3397', '8205', '1237', 'j', 'f', 'x']

SOLUTION:
c, f, j, m, n, o, p, v, w, x, y

