Instructions: 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.
Input: ['a', 'v', '7135', '7717', 'c', '3107', 'j', '9057', 'x', 'w', '8357', '1317', '53', 't', '8129', '4505', 'g', 'm', 'x', 'n', '6669', 'f', 'a', '9999', '8651', '691', '1441', '3449', '5643', 'k', '7139', 'u', '8223', '7709', 'x', '6841', '9931', '7883', 'g', '2249', '8505', 'z', '1863']
Output:
a, c, f, g, j, k, m, n, t, u, v, w, x, z