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: ['l', 'C', '3723', 'O', '2269', 'P', '4951', 'b', '1635', '149', '7665']

12, 3, 3723, 15, 2269, 16, 4951, 2, 1635, 149, 7665