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: ['3797', '6117', 'x']

A: x
****
Q: ['t', 't', 'p', '3245', 'x', 'g', 'i', 'u', '2599', '8613', 't', 'v', 'p', '5635', 'y', '9567', '5193', '8617', 'q', 'f']

A: f, g, i, p, q, t, u, v, x, y
****
Q: ['9493', 'f', 'm', '9371', 'g', 'v', '1957', '4423', '2451', 'z', 'z', 'j', '4301', '6813', '125', '9273', '6091', '4763', 'x', 'e', 'x', '5571', '9813', '9055', '2237', '4781', '9067', 'x', '9433', 'b', '4689', '1077', 'c', 'g', '4527']

A:
b, c, e, f, g, j, m, v, x, z
****