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: ['6597', '7889', 'x', 'v', 'm', 'j', 'j', 'w', 'v', '177', 'x', '8353', '5897']

SOLUTION: j, m, v, w, x

PROBLEM: ['c', '9125', '6049', '5201', 'v', '9311', 'q', '3305', 'l', 'q', '3387', '3647', 'x', '471', 'a', '5631', 't', '9679', '5423', '2569', 'w', 't', '6397', 'e', 'h', 'c', 'v', 'v']

SOLUTION: a, c, e, h, l, q, t, v, w, x

PROBLEM: ['r', '6783', 'v', 'p', 'y', 'v', '5195', 'y', '8533', '7173', '9659', 'v', '5971', '9755', 'a', 'l', 'm', '401', 'l', 'r', '6983', 'n', '8897', '2883', 'l', '8963', '9651', 'b', 'y', 'b', 'm', '7865', '501', 'y', 'z', 'y']

SOLUTION:
a, b, l, m, n, p, r, v, y, z