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: ['333', 'b', '261', 'k', 'p', '7861']

SOLUTION: b, k, p

PROBLEM: ['y', 'b', 'r', 'f', '3745', 'n', '2921', '8133', 'r']

SOLUTION: b, f, n, r, y

PROBLEM: ['x', 'o', '3445', 'l', 'd', 'q', 'w', '5909', '1335', 'r', '8947', 'z', 'g', 's', '491', '2087', 'c', 'f', 'j']

SOLUTION:
c, d, f, g, j, l, o, q, r, s, w, x, z