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: ['r', '9489', 'e', 'n', '6323', 'd', '3163', '265', '8587', '7891']

SOLUTION: d, e, n, r

PROBLEM: ['8005', 'q', 'w', 'a', 'f', 'o', '6017', '7591', 'm', 'p', 'z', 'q', 'u', 'o', 'd', '6043', 'f', '3575', 'r', '2885', 'o', '3141', '621', '2375', 't', '5397', 'h', 'b', 'i', '3785', '1551', 'i', '8879', 'g', '5237', '7111', '2057', '1743', '9895', '2613', 'i', 'z', '677']

SOLUTION: a, b, d, f, g, h, i, m, o, p, q, r, t, u, w, z

PROBLEM: ['8235', 't', '1695', '9899', '3633', 't', '1823', 'r', 'x']

SOLUTION:
r, t, x