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: ['4031', 't', 'o', 'c', 'x', '3007', '8329', '6345', '1267', '1017', 'o', 'x', 'l', '4129', 'd', '1987', '487', 'o', 'g', 'j', 'v', 'x', '3983', 'f', 'g', '5759', 'k', 'i', 'o', 'b', 'n', '683', 'j', 'o', 't', '4361', 'u']

SOLUTION: b, c, d, f, g, i, j, k, l, n, o, t, u, v, x

PROBLEM: ['q', 'g', 's', 'g', 'z', '987', '777']

SOLUTION: g, q, s, z

PROBLEM: ['f', 'a', 'm', 'i', '283', '1577', 'd', 'n', 'r', '5009', 'o', '7745', 'a', 'q', 'u', 't', '3599', '9651', '771', '8377', 'f', '4265']

SOLUTION:
a, d, f, i, m, n, o, q, r, t, u