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: ['9627', '9879', '5421', '4755', '1533', '6727', 't', '7641', 'd', '3929', 'h', '3989', '8441', 'k', 'p', '2653', 'm', 'b', 'i', '3431', '4907', '5687', 'g', 'h', '9185', '5051', 'k', '7135', '709']

SOLUTION: b, d, g, h, i, k, m, p, t

PROBLEM: ['c', '8389', 'j', '6113', '5843', 'f']

SOLUTION: c, f, j

PROBLEM: ['p', '9631', 'h', 'r', '9381', 'f', 'm', 'c', 'p', '989', 'a', '2653', '2261', 't', '447', 'c', 'a', '6939', '5655', 'n', '6919', 'm', 'a', '7653', '3821', 'k', 'g', 'y', '2095', '1551']

SOLUTION:
a, c, f, g, h, k, m, n, p, r, t, y