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: ['9953', 'l', '9619', 'F', 'U', '2257', '6197', '9429', 'I', 'P', 'f', '3589', '3881', 'o', 't']

9953, 12, 9619, 6, 21, 2257, 6197, 9429, 9, 16, 6, 3589, 3881, 15, 20