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: ['g', '1401', '4661', '7407', 'o', '9379', '2593', 'l', 'i', 'u', '71', 'v', 'z', '5743', 'e', '9957', '5297']
Student:
e, g, i, l, o, u, v, z