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: ['a', 'w', 'm', 'g', 'c', '5475', '7391', 't', '1049', 'p', 'd', '1397', 'k', 'x', 'j', '2525', 'f', '741']

SOLUTION: a, c, d, f, g, j, k, m, p, t, w, x

PROBLEM: ['1945', 't', '4477', '4439', '6569', '2021', 'y', 't', '2725', '8947', '6921', '1373', '8107', 'g', 'c', 'w', 'x', 'b', '9117', 'k', '6567', '5073', '2307', 'e', 'b', '7405', 'e', 'x', '1419', 'd', 'o', 'n', 'a', '2647', 'z', '1459', 'n', '6137', 'u', 'b', 'q', '4459']

SOLUTION: a, b, c, d, e, g, k, n, o, q, t, u, w, x, y, z

PROBLEM: ['3127', '3787', '99', '2339', '2427', '5421', '3475', 'r', 'p', 'i', 'e', '1587', 'k', 'n', '5145', 'u', '1223', '4735', '5093', '3825', 'n', 'g', 'l', 'p', 'p', '4281', 'e', 'l', 'e', 'd', 'g', '8669', 'c', '9271', '7713', 't', 't', 'a', '5171']

SOLUTION:
a, c, d, e, g, i, k, l, n, p, r, t, u