Teacher: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.
Teacher: Now, understand the problem? Solve this instance: ['6095', '9385', '5945', '155', 'r', 'x', '7697', '6131', 'a', 'g', '93', 'f', 'p', 'a', 'f', 'c', '2357', 'h', 'b', '3529', '6159', 'n', '943', '3069', 'u', 'l', '4833', 'u']
Student:
a, b, c, f, g, h, l, n, p, r, u, x