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: ['W', 'n', 'W', '6269', '3311', 'b', 'H', 'd', '6911']

23, 14, 23, 6269, 3311, 2, 8, 4, 6911