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: ['6597', '7889', 'x', 'v', 'm', 'j', 'j', 'w', 'v', '177', 'x', '8353', '5897']

SOLUTION: j, m, v, w, x

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

SOLUTION: c, f, j

PROBLEM: ['7367', 'n', '9299', 'l', '6815', 'l', '765', '1309', '6103', '5005', 'e', 't', 'x', 'p', '8419', 'x', 'p', 's', '1445']

SOLUTION:
e, l, n, p, s, t, x