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: ['F', '7507', '2533', 'O', '2733', 'r', 'a', '989', '9315', '3543', 'O', '9365', 'f', '6393', '7303', 'G', 'p', '3495', '6729']

6, 7507, 2533, 15, 2733, 18, 1, 989, 9315, 3543, 15, 9365, 6, 6393, 7303, 7, 16, 3495, 6729