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: ['H', '2921', '3609', '1695', '6551', 'z', 'Q', '815', '8909', '2993', 'J', 'c']

8, 2921, 3609, 1695, 6551, 26, 17, 815, 8909, 2993, 10, 3