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', '1129', 'f']

SOLUTION: f, i

PROBLEM: ['v', '3765', '4065', 'a', '4201', 'f', 'x', '9275', 'q', '9303']

SOLUTION: a, f, q, v, x

PROBLEM: ['4553', '1221', '9547', '9611', '1499', '1389', 'e', '4469', 'v', 'i', 'i', 'q', '5655', 'v', '787', '9337', '3511', '8951', 'z', '5229', 'z', '1729', 'o', '5775', '6459', 'u', 'p', '4207', '2869', 'k', '1329', 't', 't', 'q', 'o', 'm', 't', '8873', '921', 'z', '7']

SOLUTION:
e, i, k, m, o, p, q, t, u, v, z