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.
--------
Question: ['5345', 'f', '6605', 's', 'q', 'w', 'p', 'o', 's', 'u', 'i', '7339', '8379', 'h', '9547', 'b']

Answer: b, f, h, i, o, p, q, s, u, w


Question: ['w', '8777', 'y', 'e', '8015', 't', 'w', '53', '9149', 'e', 'k', '1837', 'b', 's', '4007', '4905']

Answer: b, e, k, s, t, w, y


Question: ['3855', '8993', 'n', 'o', 'w', '8523', 'r', '7523', 's', '8541', '33', '7709', '2535', '6143', 'o', '347', 'g', 'n', 'z', '5933', '1837', 'p']

Answer:
g, n, o, p, r, s, w, z