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: ['u', 'w', '401', 't', 'g', 'h', 'g', '8073', '9597', '1347', '7835', '5007', '977', 'p', '7679', 'b', '4883', '4931', '999', 'r', '1181', 'x', '2063', 'l', 'w', 'i', 'l', 'x', 'i', '9057', '5007', 'w', '743', '1635', 'y', 'f', '9227', 'z', '5227', 'd', '7129', 'k', '7657']

SOLUTION: b, d, f, g, h, i, k, l, p, r, t, u, w, x, y, z

PROBLEM: ['5181', '8651', '963', '2111', 'g', '7913', '8335', 'o', '1387', '9225', '6517', 's', 'r', '2291', '3699', 'y', 'y', '4223', 'i', '9109', 'm', 's', '8585', 'l']

SOLUTION: g, i, l, m, o, r, s, y

PROBLEM: ['j', 's', 'n', 'r', 'a', '7675', '9261', 'b', '6679', 'f', '9007', 'l', '2029', 'l', '6745', 's', 'p', 'a', 'f', '8351', 'n', 'h', '4599', '3195', 'j', '4367', '3605', '7753']

SOLUTION:
a, b, f, h, j, l, n, p, r, s