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: ['5911', '2287', 'Z', 'a', '3615', '6721', 'S', 'x', '2547', 'v', '9457', 'E', 'O', 'k', 'p']

5911, 2287, 26, 1, 3615, 6721, 19, 24, 2547, 22, 9457, 5, 15, 11, 16