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: ['c', '1693', 'l', 'u', 'x', '3609', 'h', '4159']

Answer: c, h, l, u, x


Question: ['i', '4447', 'g', 'o', 'j', 'p', 'l', 'q', 'o', '8777', 'r', 'v', '961', '6083']

Answer: g, i, j, l, o, p, q, r, v


Question: ['r', '7651', 'g', 'p', 'f', '3915', '5535', 't', 'n', 'e', 'a', 'z', 'k', '9133', '3515', '555', '9423', '2393', '9901', '6547']

Answer:
a, e, f, g, k, n, p, r, t, z