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: ['g', 'p', '2925', 'n', 'o', 'y', '6381', 'l', '4963', 'g', 'm', 'u', 't', '9389', '3787', '7713', '1251', '779', 'i', 'w', '9869', 'y', 'y', '3881', 'k', 't']

SOLUTION: g, i, k, l, m, n, o, p, t, u, w, y

PROBLEM: ['5337', '4877', '9443', '3445', 'u', '2571', 't', 'n', 'x', '1985', '5145', '3397', 'p', '9259', 's', 'x', 'u', 'c', 'g', 't', 'j', '829', '8273', 'e', 'j', 'r', 'x', '865', '4773', 'h', '4407', '8591']

SOLUTION: c, e, g, h, j, n, p, r, s, t, u, x

PROBLEM: ['w', 'c', '1701', '4519', '4543', 'q', '5797', 'j', 'w', '7343', 'z', '1471', '8913', '2677', '1973', '3033', 'w', 'y', '9139', 'r', 'd', '1473', 'd', 'l', 'x', 'b', 't', 's', '5225']

SOLUTION:
b, c, d, j, l, q, r, s, t, w, x, y, z