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: ['U', 'q', 'Z', 'v', '8739', 'Q', 'H', 'f', '4469', '8875', 'J', 'w', '5409']

21, 17, 26, 22, 8739, 17, 8, 6, 4469, 8875, 10, 23, 5409