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: ['i', '9215', 'n', 'p', '4815', '8757', 'm', '1755', 'c', 'z']

SOLUTION: c, i, m, n, p, z

PROBLEM: ['k', '1995', 'b', '2581', 'x', '2639', 'i', '6761', '2701', 'd', '6993', '9375', 'r', 'm', '249', '8115', '8179', 't', '4901', 'i', '6197', '2809', 'e', 's', 'j', '4261', 'f', '6649', '7527', '3839', '5651', '9287', 'n', '2505', 's', 'q', '2825', 'g']

SOLUTION: b, d, e, f, g, i, j, k, m, n, q, r, s, t, x

PROBLEM: ['e', '1527', '189', '5091', '3283', '8493', 'x', 'u', '967', '4839', 'v', 'l', 'h', '3595', 'x']

SOLUTION:
e, h, l, u, v, x