Instructions: 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.
Input: ['7217', 'z', 'j', '833', '7941', 'p', 'u', 'x', 'v', 'q', '3859', '9699', 'l', '9103', 'x', '6247', 'v', '1603', '5839', 'e', 'c', '6551', 't', '5137', '8745', '7889', '3797', 'd', '9541', 'a', '547', 'c', 'p', '4023', '3863', 't', '6299', '4157', '2059', '4163', '5453', '5327', '4837']
Output:
a, c, d, e, j, l, p, q, t, u, v, x, z