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: ['8811', '4289', 'P', '7151', 'f', 'a', '4563', 'A', 'h', '7765', 'R', 'U', '8539']

8811, 4289, 16, 7151, 6, 1, 4563, 1, 8, 7765, 18, 21, 8539