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: ['459', '1729', 'b', 'c', '9619', '4461', '4347', '6733', 'i', '3631', 's', 'j', 'i', 'r', '5293', 'q', '7397', '4309', 'c', 'n', 'k', '197', 'q', '8139']

SOLUTION: b, c, i, j, k, n, q, r, s

PROBLEM: ['j', 'a', 'z', 'h', '4129', '4159', 'm', 'o', 'o', '1193', '2905', '3083', 'q', 't', 'm', 'o', '673', '7547', 'n', 'c', 'r', 't', '2897', '4959', 'z', '2377', 'y', '7977', 'u', 'b', 's', 'w', 'e', 'd', '8051']

SOLUTION: a, b, c, d, e, h, j, m, n, o, q, r, s, t, u, w, y, z

PROBLEM: ['u', 'w', '7711', '4525', 'l', '2401', 'w', 'x', '6923', '3525', 's', 'g', '5603', '4631', 'j', '4109', '8671', 'q', '2867', 'x', 'l', 'g', '11', 'n', '1045', '8743', 'a', '4201', 'p', 'q', '8625', 'v']

SOLUTION:
a, g, j, l, n, p, q, s, u, v, w, x