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: ['9271', '6393', '6005', 'x', '2301', '3999', 'p', 'z', 'j', '1033', '7555', 'r', 'r', 'y', '8917', '5939', '4031', 'e', '8095', 'g', '6095', 'a', '4133', '6471', '2129', '8021', '1093', 't', '8805', '545', 'k', '3249', 'l', '1561', '9909', 's', '1963', 'o']

SOLUTION: a, e, g, j, k, l, o, p, r, s, t, x, y, z

PROBLEM: ['p', '2923', 'e', 'k', '5433', '605', '5079', 'k', 'p', 'x', '4845', '4099', '6795']

SOLUTION: e, k, p, x

PROBLEM: ['3887', '815', '5091', 'q', 'l', 'c', '4247', 'n', 'j', 'o', 'q', 'h', 'y', '19', 'j', 'w', 'v', 'l', 's', 'x', 'p', 'w', '8581', 'd', '4541', 'u', '6371', '4415', 'g', 'b', '939', '8941', '8735', '9671']

SOLUTION:
b, c, d, g, h, j, l, n, o, p, q, s, u, v, w, x, y