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: ['g', 'h', 'g', 'g', 's', 'h', '2849', '2705', '1185', 'x', '5789', '8221', 'e', 'x', 'g', 'b', '4903', 'q', '1563', 'r', 'k', 't', '9047', 'p', 'p', '9397', 'u', '7473', 'f', 'o', 'y', '1957', '1039', '9905', 'i', '4829', 'q', 'w', 'k', 'p', 't', '563', 'g', 'l']

SOLUTION: b, e, f, g, h, i, k, l, o, p, q, r, s, t, u, w, x, y

PROBLEM: ['k', 'c', 'i']

SOLUTION: c, i, k

PROBLEM: ['2613', 's', 's', '1589', 'h', '1403', '3151', '6097', '1913', '8731', '3471', 'd', '753', 'g', '3481', '6403', 'i', 'g', '6667', '825', '3601', 'f', 'a', 't', '7201', 'h', 't', 'p', 'l', 'k', 'a', 'e', 'a', 'q', 'k', '7085', '993', '6721', 'd', '8249', '8757', 'u']

SOLUTION:
a, d, e, f, g, h, i, k, l, p, q, s, t, u