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.
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Question: ['c', '7039', 'g', '1899', 'r', '507', 'c', '2587', '3865', '1729', '3927', 'r', '3535', '2791', 'm', 'l', 'r']

Answer: c, g, l, m, r


Question: ['9483', '501', 'j', 'k', '3103']

Answer: j, k


Question: ['2165', '5031', 'y', '6639', 'c', '7565', '525', '3363', '3271', '901', '5299', 'm', 'o', '8847', '5999', 'e', '6917', '3125', 'e', '67', '4637', '9267', '867', 'l', '2427', 'k', '4791']

Answer:
c, e, k, l, m, o, y