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: ['2381', '2865', '4821', 'n', 'u', 's', 'p', 'v', 'v', 'n', '1349', '7903', 'm', '193', 't', 'p', 'c', '3521', 'a', 't', '8281', 'i', '151', '4783', 'm', '3387', '9551', 'z', 'q', 'v', '4549', '4411', 'u', '8735', '2645', '359', '2871', '5923', '5071', 'c', '9843', 'i']

SOLUTION: a, c, i, m, n, p, q, s, t, u, v, z

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

SOLUTION: b, t, u

PROBLEM: ['7673', 'v', 'z', '5767', 'y', 'm', '3315', '1145', '6479', '3195', '8667']

SOLUTION:
m, v, y, z