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: ['p', 'p', '7899', 'u', '971', '7289', 't', '5217', 'k', 'z', 'y', 'y', '6905', '9499', '4085', 'x', '955', 'v', 'j', '9049', '7927', '1757', '193', '2181']

Answer: j, k, p, t, u, v, x, y, z


Question: ['8235', 't', '1695', '9899', '3633', 't', '1823', 'r', 'x']

Answer: r, t, x


Question: ['8469', '805', 'u', 'y', '6423', '8663', '5695', '8089', 'c', 'i', '1303', '5873', '6839', '4903', '2087', 't', '3789', 'o', 'n', 'e', 'i', 'b', 'v', 'j', '3753', '7895', '7639']

Answer:
b, c, e, i, j, n, o, t, u, v, y