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: ['333', 'b', '261', 'k', 'p', '7861']

Answer: b, k, p


Question: ['f', '3409', 'i', '4147', '1745', '6007', 'l', 'd', 'i']

Answer: d, f, i, l


Question: ['6467', '4995', '1255', 'n', 'o', '7065', '1457', '8635', 'b', 'd', 't', 'd', '9621', '649', 'o', '8761', '2207', 'd', '8703', 'k']

Answer:
b, d, k, n, o, t