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: ['215', '7723', '8003', '9303', '2287', '4523', 'U', '6333', '5559', '9939']

215, 7723, 8003, 9303, 2287, 4523, 21, 6333, 5559, 9939