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: ['2165', 'f', '5081', 's']

SOLUTION: f, s

PROBLEM: ['2521', '8027', 'm', '193', '615', 'l', '1947', '5949', '6307', 'r', '1015', '743', 'v', '6949', 'b', 'g', '8841', 'c', 'b', '2879']

SOLUTION: b, c, g, l, m, r, v

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