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: ['N', '8821', 'U', 'X', 'N', '4125', 's', 'C', '9141']

14, 8821, 21, 24, 14, 4125, 19, 3, 9141