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', 'x', 'n', 'w', '8915', 'd', 'd', 'd', '6025', '7861']

SOLUTION: d, i, n, w, x

PROBLEM: ['6411', 'x', 'i', '267', 'z', 'e', '5483', '8033', '3697', 'z', '4167', 'e', 'f', '7229', 'i', 't', '2197', 'g']

SOLUTION: e, f, g, i, t, x, z

PROBLEM: ['d', '7829', '679', '9869', 'e', 'q', '455', 'n', '9443', 'p', '7785', 'f', '6739', '8769', 'd', 'g', 'o', '3047', '3959', 'g', '8257', '8493']

SOLUTION:
d, e, f, g, n, o, p, q