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: ['t', 'u', '6101', 'p', '6657', '1545', 'r', '6235', '1341', '2521', '291', '8795', '3719', 'y', '4979', '3219', 'g', '2617', '9073', '7317', '4263', '9945', 'v', 'd', 'b', 'k', '2025']
Student:
b, d, g, k, p, r, t, u, v, y