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: ['q', 'c', 'o', 'e', 'n', 'q', 'w', '9475', 'w', '863', 'r', '2219', '3483', '5035', '8209', '7957', 'b', '3735', '1423', 'l', '3409', '7639', 'd']

SOLUTION: b, c, d, e, l, n, o, q, r, w

PROBLEM: ['1367', 'h', '4153', '1587', 'h', 'b', 'n', 'u', 'n']

SOLUTION: b, h, n, u

PROBLEM: ['q', '8521', '1825', '3851', '1757', '3483', '9657', 'w', '3007', '5733', '7055', '3175', '7275', '1747', '265', '7077', 'g', '4591', '1423', '4051', '5221', '8915', 'w', 'u', 'c', '5177', '7929', '4281', 'w', 'l', 'o', 's', 's', 'm', 'm', '531', 'd', 'v', 'g', '5849', 'c', '6203', '3521']

SOLUTION:
c, d, g, l, m, o, q, s, u, v, w