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: ['i', 's']

Answer: i, s


Question: ['9385', '4021', 'y', '9629', 'u', '7623', 'd', '5155', 'x', '2605', '8893', 'l', 'p', 'a', 'm', '6699', 'i', '4503', '6623', 'm', 'l', '6115', 'p', 'w', '9691', '811', '4769', '2659', 'x', 'c', '6513', '5499', 's', 'q', 'f', 'v', 'z', 'w', 'z', '1361']

Answer: a, c, d, f, i, l, m, p, q, s, u, v, w, x, y, z


Question: ['6509', 'u', 'z', 'b', '1891', '1315', 'p', 'o', 'r', '2001', '133', 'z', 'g', 'd', '4037', '6435', '4879', 'q', 't', '925', 'i', 'y', 's', 'i']

Answer:
b, d, g, i, o, p, q, r, s, t, u, y, z