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: ['7777', '6223', 'k', 'k', 'd', '9743', '189', '7705', 'c', '6115', '4275']

Answer: c, d, k


Question: ['7055', '2573', '1713', 'x', 'm']

Answer: m, x


Question: ['s', '4913', '9679', 'j', '8111', '3059', '4041', '5877', '923', 'q', '2865', '2483', 'm', '3753', '5321', '8213', 't', 'b', 's', '7683', '527', 'c', 'q', '4497', '1437', '4457', '7413', '6937']

Answer:
b, c, j, m, q, s, t