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? If you are still confused, see the following example:
['8129', 'a', '4245', 'y', 'm', 'a']
Solution: a, m, y
Reason: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.

Now, solve this instance: ['t', '6277', '7769', '8179', 's', '379', '6201', '4415', 'w', 'l', '3579', 'a', '4191', 't', 'p', 'i', '6865', 'v', 'e', '5325', '1031', '8431', '931', '9241', '8499', 'u', '9981', '1045', 'z', '8309', 'j', 'u', '4811', 'x', '513', '9693', '519', 'z', '7477', 'h', 'r', '4193', 'x', '5293', '3999']
Student:
a, e, h, i, j, l, p, r, s, t, u, v, w, x, z