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.

Input: Consider Input: ['7997', 'm']

Output: m


Input: Consider Input: ['575', 'u', 'c', '8113', '2853', '3661', '9427', '3071', '4069', '835', 'w', 't', 'w', 't', 'v', 'g', 'c', '5497', '1703', '8433', 'g', '3545', '2887', 'z', 'a', '2241', '5799', '5915', 'u', '4015', '8327', 'z', 'a', 'w', '8311', '289', '8575', 't', 'b', '2873', 'r', 'z', 'x', '1165', '9881']

Output: a, b, c, g, r, t, u, v, w, x, z


Input: Consider Input: ['u', '6127', '2885', '2879', 'a', 'u', '2639', '6917', '4381', 'm', '4019', '7985', 'y', 'z', '5261', '3601', '8473', '6159', 'a', '2875', '8391', '4733', 'g', 'l', '3411', 'a']


Output: a, g, l, m, u, y, z