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: ['4653', 'e', 'c', 'j', '6739', '3963', 'q', '4649', 'v', 's', 'j', '9757', '8075', '6253', '4365', 's', '9101', 'd', '6989', 't', '5687', '7389', '139', '4029', '5073', 'q', 'e', '2455', '1075', 'j', '1329', 'l', '4689', 't', 'z', '4179', 's', 'l', 'w', 'n', '6569', '8907', 'v', '605', 'y']

SOLUTION: c, d, e, j, l, n, q, s, t, v, w, y, z

PROBLEM: ['c', '4881', '6893', '3729', 'j', '2385', 'q', 'v']

SOLUTION: c, j, q, v

PROBLEM: ['3523', '4059', '4925', '9501', 'd', '7153', '1997', 'o', 'j', '811', '2421', 'b', '8683', '1329', 'l', 'e', 'a', 'v', '147', 'm', 'v', '8513', 'w', '3885', 'w', 'x', 'n', 'i', '1601', 'f', 't', 'b', '8239', '695', 'f', 'i', '2449', 'z']

SOLUTION:
a, b, d, e, f, i, j, l, m, n, o, t, v, w, x, z