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', '6503', 'z', '2625', '7281', 'w', '2607', 'O', 'w', '9063', 'M', 'u']

12, 6503, 26, 2625, 7281, 23, 2607, 15, 23, 9063, 13, 21