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: ['a', 'c', '8389', '5975', '7605', '5569', '5595', '2329', '3931', '7203', 'U']

1, 3, 8389, 5975, 7605, 5569, 5595, 2329, 3931, 7203, 21