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: ['6143', 'y', '5505', '9813', 'r', 'v', 'u', '8681', '2387', 'u', 'o', 'm', '9793', 'm']

Answer: m, o, r, u, v, y


Question: ['6575', '2057', '2135', '6259', '7741', '4919', '7461', 'v', '401', 'h', 'u', '2391', '2181', 'y', '9273', 'd', 'b', 's', '7993', '9323', 'b', '7015']

Answer: b, d, h, s, u, v, y


Question: ['p', 'z', '9067', 'l', '6237', '5013', 'r', 'l', '7647', '3081', '827', 'k', '1025', 'u', '5217', '4397', 'j', '7011', '505', '9031', '2261', '2845', '1301', '3965', 'd', '8219', '1055', '7605', 'h', 't', '1035', 'r', 'x', 'f', '6621', 'l', '7339', '8319']

Answer:
d, f, h, j, k, l, p, r, t, u, x, z