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: ['f', '9027', 'z', '9601', 'w', '7747', '1135', 'j', '1871', 'd', 'u', 'f', 'd', 'x', 'k', '2009', 't', '4625', 'm', '1619', 'm', 'm', '3107', 'x', '3957', '2495', 'j', '201', 'a', '4635', 'r', '7407', 'b', 'r', 'z']

SOLUTION: a, b, d, f, j, k, m, r, t, u, w, x, z

PROBLEM: ['4041', 'l', 'g', '9571', '9295', '1395', 'l', 'p', 'f', 'w', 'g', '1721', '2421', 'w', 'z', '2235', 'p', '7851']

SOLUTION: f, g, l, p, w, z

PROBLEM: ['w', 'c', 'l', 'z', '2557', '6927', 'i', 'n', 'a', 't', 'z', '2253', '3901', '6227', '9269', '7073', 'y', '1339', '3937', 'z', '7431', 'q', 's']

SOLUTION:
a, c, i, l, n, q, s, t, w, y, z