instruction:
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.
question:
['w', 'o', 'l', '5331', 'k', '9325', '6759', '7931', '8185', 'w', 'h', 'h', 'x', '4357', '6845', 'v', 'o', '8401', 'u', 'g', 'f', 'j', 'j', '2493', '4753', 'c', 'm', '1469', '4307', 'm', '2737', 'n', 'y']
answer:
c, f, g, h, j, k, l, m, n, o, u, v, w, x, y


question:
['y', 'g', '107', '4899', '6357', '9777', 'k', '1865', '7029', 'q', 'x', '7051', 's', '6125', '4285', '2731', 'z', 'a', '737', '6137']
answer:
a, g, k, q, s, x, y, z


question:
['i', '2397', '9117', '2431', 'o', '6437', 'h', '9215', '2605', '5311', 'v', 'h', 's', 't', 'r', 'u', '9855', '3375', '1909', '537', 'r', '6331', 'r', '1205', 'x', '7791', 'z', '4081', 'a', '3509', '3161', 'l']
answer:

a, h, i, l, o, r, s, t, u, v, x, z