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: ['c', '4049', 'w', '9777', '5531', 'm', 'k', 'g', '4791', 's', 'l', 'm', 'r', 'r', 's', '5709', '4249', 'o', 'e']
A:
c, e, g, k, l, m, o, r, s, w