Definition: In this task, you are given an input list A. You need to convert all the alphabets in the list with a number representing their position in the English alphabet. E.g., replace A by 1, B by 2, a by 1, b by 2, and so on.
Input: ['S', '9519', '8927', 'U', '1967', 'O', '7089', 'M', '5003', '1311', 'z', '3555', 'i', '8339', 'J', '7473']

19, 9519, 8927, 21, 1967, 15, 7089, 13, 5003, 1311, 26, 3555, 9, 8339, 10, 7473