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: ['2165', 'f', '5081', 's']

Answer: f, s


Question: ['m', '7807', 'n', 'w', '5097', '1023', '2723', 'u', '3055', '7285', 'f', 'm', 'w', '5197', '9743', '7519', '4451', 'c', 't', '1939', '5847']

Answer: c, f, m, n, t, u, w


Question: ['867', 'o', 'v', '999', '3849', '9995', 's', 'f', '201', 'i', 'z', '5495', 'c', 'e', 'y', 'k', 'o', 'c', '1505', 'i', '9573', 'f', 'l', 'y', 't', 'p', 'm', 's', '3575', 's']

Answer:
c, e, f, i, k, l, m, o, p, s, t, v, y, z