TASK DEFINITION: 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.
PROBLEM: ['2103', '7937', 'v', '7641', '6609', '269', '4463', '4333', 'c', '8407', '4883', '6283', 'a', '8643', '3365', '1929', 'v', 'o', '2107', '7453', '9157', '5581', '5187', 'f', 'k', '8227', '6295', 'b', 'y', '4995', '1187', 'k', 'n', 'p', 'z', '8165', 'n', '7345', 'l']

SOLUTION: a, b, c, f, k, l, n, o, p, v, y, z

PROBLEM: ['h', 'g', '4563', 'v', 'm', '107']

SOLUTION: g, h, m, v

PROBLEM: ['2781', '7229', 'm', 'z', '2867', 'n', '5613', 'c', '6897', 'b', '771', '905', '3497', 'p', '6031', 'o', 'u', 'q', 'f', '577', '5699', '7211', '9377', '8327', '6251', '5953', '8257', 'c', '3117', 'j', 'i', 'v', '1861', '2217', '1509', 'z', '2807', 't', '123', 'j', '8473']

SOLUTION:
b, c, f, i, j, m, n, o, p, q, t, u, v, z