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: ['6863', '853', 'O', '9577', 'H', 'Z', 'R', 'r']

6863, 853, 15, 9577, 8, 26, 18, 18