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: ['3019', 'g', 'q', 'u', '611', 'z', '3671', '8119', '1679', 'h', '2631', '655', 'k', '2837', 'e', 'f', 'e', 'f']

SOLUTION: e, f, g, h, k, q, u, z

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: ['1779', 'p', 'd', 'f', '6979', '9243', '6799', '15', 'b', 'a', '2307', 'o', 'j', 'k', 'o', 'j', '1265', 'a', 'h', 'u', '3243', '4455', 'u', 'x', 'l', 'a', 'v', 't', '7961', 'x']

SOLUTION:
a, b, d, f, h, j, k, l, o, p, t, u, v, x