Detailed 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.
Q: ['l', 'w', 'n', '443', 'l', 's', '253', '7171', '9951', 's', 'c', '8847', 'l', '3915', 's', 'c', '75', 'n']
A:
c, l, n, s, w