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.

Q: ['u', 'i', '1185', '3795', '5417', 'k', 'b', '2629', '2635', 'z']

A: b, i, k, u, z
****
Q: ['l', '6313', '3199', 'w', '249', '8747', '7391', '3871', '173', 'x', 'o', '8647', '4413', '3645', '6123', '701', 'q', '2147', '4289', '7333', '533']

A: l, o, q, w, x
****
Q: ['a', '5321', '6433', '1557', 'y', '4989', '9655', '5313', '4129', '4725', '2415', '1001', '3623', '5337', 'p', 'x', 's', 'c', 'i', 'g', '5019', '6691', 'w', '3591', 'x', 'k']

A:
a, c, g, i, k, p, s, w, x, y
****