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: ['C', '6545', 'Z', 'a', '139', '2721', '1379', 'Z', 'N', '6261', 'c', '5109', '6653', 'd', '1245', 'H', 'J', '5609', 'G', '3781', '6845', 'O', '6751']

3, 6545, 26, 1, 139, 2721, 1379, 26, 14, 6261, 3, 5109, 6653, 4, 1245, 8, 10, 5609, 7, 3781, 6845, 15, 6751