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.
Input: ['t', 'a', 'd', 'u', '9919', '9339', '1459', '719', 'z', 'e']

a, d, e, t, u, z