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.
One example is below.
Q: ['8129', 'a', '4245', 'y', 'm', 'a']
A: a, m, y
Rationale: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.
Q: ['5355', '1273', '1611', '9377', '9109', '1037', 's', '8145', '4437', '353', 'v', '6553', '2851', '4515', '7657', '361', 'c', 'n', 't', 'x', 'i', '633', '6785', '3153', 'v', 'f', '5765', '4413', '2767', '8237', '5897', 'b', '8999', 'x', '7677', '8379', 'q', 'o', 'i', '6947', '9563', 'c', '7707', 't']
A:
b, c, f, i, n, o, q, s, t, v, x