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: ['o', 'm', '8015', '787', '4787', '1727', 'f', 'e', 'c']

SOLUTION: c, e, f, m, o

PROBLEM: ['t', 'a', '2481', '2841', 'a', '2871', 'm', '4435', 'g', '8201', '4351', '9045', 'o']

SOLUTION: a, g, m, o, t

PROBLEM: ['9229', 'z', 'i', '1827', '6863', '193', '7047', '9677', 'b', '1923', 'a', 'b', '9663', '5821', 'm', 'y', '7961', 'a', '8591', '7379']

SOLUTION:
a, b, i, m, y, z