Definition: 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: ['t', '6645', '9723', 'p', 'g', 'h', 'h', 'x', '1921', '4331', 'p', 'f']

f, g, h, p, t, x