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: ['s', 'u', 'y', '5081', 'd', '3299', '6247', 'r', 'h', '4537', '7701', 'r', 'y', '6919', '9905', 'i', '2813', '675', 'w', '3587', '917', '9985', 'e', '1015', '1873', 'g', 'a', '787']
Student:
a, d, e, g, h, i, r, s, u, w, y