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: ['3599', '7755', '4313', '6491', 'c', 'g', 't', 'x', '8619', 'x', 'd', 'o', 'o', '4541', '9507', '43', '9773', '3473', 'v', '2761', 'l', 'p', '8155', 'e', '6105', 'm', '1571', '9203', 'p', '2693', '2147', 'r', '2065', 'p', '5721', '6117']
Output:
c, d, e, g, l, m, o, p, r, t, v, x