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: ['3797', '4139', 'u', 'P', '9199', '1541', 'd']

3797, 4139, 21, 16, 9199, 1541, 4