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.
--------
Question: ['2459', '3709', 'f', '8673', '9313', 'm', 'd', 'g', 'c', 'g', 'u', 'f', 'p', 'i', '8771', '3613', '9669', '6221', '1211', '8331', '2295', 'b', 'f', 'm', '1377', '9831', '1751', 'k', '4831', 'm', '2747', '3435', '4543', 'c', '1729', 'e', '7093', '397', 'm', '383', '2019']

Answer: b, c, d, e, f, g, i, k, m, p, u


Question: ['1979', 'b', 't', '1101', '7953', '2451', '7539', '6833', 'u', '49']

Answer: b, t, u


Question: ['m', 'e', '8177', '7451', 'b', 'z', '7231', '3117', 'z', '2933', 'y', 'u', '1419', '281']

Answer:
b, e, m, u, y, z