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: ['4299', 'b', '4171', '7639', '6609', '927', '5249', 'o', 'p', '9851', 'e', '1311', '3777', '7799', '7687', '8809', 'c', 'r', '47', '1925', '1847', 'r', 'd', 'r', '1871', '5935', 'r', '2283', 'p', 'p', '2727', 'c', 'i', '7357', 'y', '5103', '6115', 'q', 'w', 'u', '9201', '4221', '7717', 'o']

Answer: b, c, d, e, i, o, p, q, r, u, w, y


Question: ['t', 'r', '2959', '2517', 'a', '9959', '729', '511', 'y', 'r', '465', 'c', '687', 'm', 'b', 'm', '3449', '9713', 'g', '8275', '8823', 'a', 'z', 'w', '2185', '6283', '8457', '8137', '7163', '8329']

Answer: a, b, c, g, m, r, t, w, y, z


Question: ['z', 'x', 'a', '1951', 'p', 'w', 'g', '3887', 'u', 'y', '4987', '9581', 'h', 'i', 'a', '9159', 'u', '5037', 'z', 'r', '6597', '1443', '4427']

Answer:
a, g, h, i, p, r, u, w, x, y, z