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: ['5859', 'x', 'z', 'v', 'l', 'z', 'g', 't', 'x', '341', '7023', '4937', 'b', 'n', 'y', 't', 's', '1369', '4461', 'f', '1315', 'l', '5221', '6583', 'h', 'j', 't']

SOLUTION: b, f, g, h, j, l, n, s, t, v, x, y, z

PROBLEM: ['w', '5341', 'b', '6243', 'v', '877', '1087', '6763', '5241', '3369', '9119', 't', 'v', 'j', '8261', 'o', 'b']

SOLUTION: b, j, o, t, v, w

PROBLEM: ['2771', 'e', 'l', '4685', '8611', '3151', 'w', 'h', '8197', '9343', '1357', '1191', 'm', '9341', '6439', '9381', '8745', '637', 'n', 'a', 'i', 'm', '241', '4285', '6251', '8641', '3213', 's']

SOLUTION:
a, e, h, i, l, m, n, s, w