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.

Q: ['y', 'i', '257', '3695', 's', '6717', '4817', '4117']

A: i, s, y
****
Q: ['6955', '721', '2763', '8121', '9109', '6341', 'p', 't', 'x', '6963', '1137', 'z', 'u', '1949', '7029', 't', '9539', 'a', 'u', '1873']

A: a, p, t, u, x, z
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Q: ['t', 'c', 'm', 'c', 'm', 'f', '1323', '4267', 'l', 'u', 'd', 's', 'm', 'q']

A:
c, d, f, l, m, q, s, t, u
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